FBI agents investigating Hillary Clinton's use of a private email server while Secretary of State knew early last month that messages recovered in a separate probe might be relevant to their case, but waited weeks before briefing the FBI director, according to people familiar with the case.

Director James Comey has written that he was informed of the development on Friday, and he sent a letter to legislators the next day letting them know that he thought the team should take "appropriate investigative steps designed to allow investigators to review these emails".

That missive ignited a political firestorm less than two weeks before the election. Almost instantly, Comey came under intense criticism for his timing and for bucking the Justice Department's guidance not to tell Congress about the development. And his announcement means that Clinton could have to contend with the news that the FBI has resumed its investigation of her use of a private email server - without any clarity on whether its investigators will find anything significant - up to and beyond Election Day.

LISTEN: Florida-based journalist Matt Peddie spoke with Mike Hosking about Clinton's emails

Advertisement

The FBI has obtained a warrant to search the emails found on a computer used by former congressman Anthony Weiner that may contain evidence relevant to the investigation into Clinton's private email server, according to law enforcement officials. The warrant was obtained in New York, as FBI agents there have possession of the laptop.

One official said the total number of emails recovered in the Weiner investigation is close to 650,000 - though that reflects many emails that are not relevant to the Clinton investigation. However, officials familiar with the case said the messages include a significant amount of correspondence associated with Clinton and her top aide Huma Abedin, Weiner's estranged wife.

People familiar with the case said that agents on the Clinton email team had known about the messages since soon after New York FBI agents seized a computer related to their investigation into Weiner, who has been accused of exchanging explicit messages with a 15-year-old girl.

Officials said the agents probing Clinton's private email server didn't tell the director immediately because they were trying to better assess what they had. "It's a step-by-step process," said one senior law enforcement official. "There are many steps along the way that get you to a place where the director can be appropriately briefed in order to make a decision" about whether to move forward.

Investigators will now look at whether the newly uncovered emails contain classified information or other evidence that could help advance the Clinton email probe. It is possible, though, that the messages could be duplicative of others already recovered elsewhere or that they could be a collection of benign, personal notes.

Several law enforcement officials with technical expertise said it is generally not difficult to create software to analyse such emails, searching for terms like "secret" or "top-secret" or any mention of places with classified operations, such as Pakistan. Agents should also be able to figure out quickly how many of the emails duplicate those that have already turned up. "You could automate that pretty quickly," said one law enforcement official.

What will take more time, however, is making conclusions about whether any of the emails include classified information. That process, former FBI officials have said, could be cumbersome and drag on after the election. Investigators would have to read those for potentially relevant information, and, if there were questions about their classification, send them to other agencies for review.

But no one involved in the investigation is trying to delay, officials say.

"This is not a team that sits on its hands," said one official.

Abedin has told people that she is unsure how her emails could have ended up on a device she viewed as belonging to her husband, according to a person familiar with the investigation and civil litigation over the matter.

An announcement from the FBI in early October, when the emails were discovered, might have been less politically damaging for Clinton than one coming less than two weeks before the November 8 (November 9 NZT) election. The FBI declined to comment.

Comey wrote in his letter to Congress, "We don't know the significance of this newly discovered collection of emails," and federal law enforcement officials have said that investigators on the Clinton email team still had yet to thoroughly review them.

Comey in July announced that he was recommending that the investigation into Clinton's use of a private email server while she was Secretary of State be closed without charges. But he said investigators had found classified information on the server and characterised Clinton's and her aides' conduct as "extremely careless".

Legislators on both sides of the political aisle are likely to raise questions about why the team investigating Clinton's private email took so long to brief Comey. Clinton and her backers have pushed aggressively for the bureau to release more information about its findings and criticised the agency for making its work public without knowing more. Republican presidential nominee Donald Trump has called the matter "the biggest scandal since Watergate" and suggested, without evidence to support his claim, that the case against Clinton was now "so overwhelming".

A Washington Post-ABC News tracking poll found that more than 6 in 10 likely voters said the FBI's announcement would make no difference in their vote. A little more than 3 in 10 said the news made them less likely to support Clinton, though about two-thirds of those were Republicans or Republican-leaning independents.

Meanwhile, Senate Democratic leader Harry Reid sent a letter to Comey yesterday suggesting he violated the Hatch Act, which bars the use of a federal government position to influence an election.

"Through your partisan actions, you may have broken the law," Reid, a senator from Nevada, said in the letter to Comey.

And Richard Painter, a professor at the University of Minnesota Law School and the chief White House ethics lawyer from 2005 to 2007, said he filed a complaint over Comey's actions with the Office of Special Counsel, which investigates Hatch Act violations.

"We cannot allow FBI or Justice Department officials to unnecessarily publicise pending investigations concerning candidates of either party while an election is under way. That is an abuse of power," he said in a column in the New York Times.

However, Daniel Richman, a former federal prosecutor who now teaches at Columbia Law School, called the allegations that Comey improperly tried to influence the election "inane".

"Comey's critics cannot show his letter violated the Hatch Act unless they can prove that the FBI director was intending to influence the election rather than inform Congress, which was Comey's stated aim," said Richman, who said he had advised Comey on law enforcement policy but not this issue.

FBI Director James Comey. Photo / AP
FBI Director James Comey. Photo / AP

Agents wanted to probe Clinton Foundation

FBI agents argued - based at least in part on news accounts - earlier this year that the Clinton Foundation should be investigated for potentially giving donors special political access and favours. The Justice Department's public integrity unit said they did not have enough evidence to move forward.

The Clinton Foundation said it was never contacted by the FBI, suggesting the bureau's efforts were in a preliminary stage as prosecutors weighed in. But agents in New York have sought to keep their inquiries alive, feuding with the Justice Department about the lengths to which they can go, according to people familiar with the matter.

That infighting became public yesterday, when the Wall Street Journal published a detailed account of interactions between prosecutors and FBI officials over the politically sensitive subject.

The FBI's New York field office was one of a few that - in at least some small way - were looking into topics that touched on the Clinton Foundation's work, according to people familiar with the matter. Agents in New York wanted to examine allegations of corruption and conflicts of interest that have swirled around the charitable organisation of the Clinton family, the people said.

It is unclear what, if any, evidence they had to substantiate those allegations, particularly through subpoenas or search warrants. One person familiar with the matter said their presentation drew at least in part from media accounts over various foundation-related controversies.

That person, as with the others in this story, spoke on the condition of anonymity out of fear of facing professional consequences for discussing the politically sensitive matter.

Republicans have long been critical of the Clinton Foundation, in particular Hillary Clinton's dealings with its donors while she was Secretary of State. When FBI agents met prosecutors to argue for a more significant look into the foundation, the GOP was especially eager to attack the organisation during the height of the political primary season.

The Clinton Foundation, which Bill Clinton created soon after leaving the White House in 2001, has become one of the world's fastest-growing philanthropies. It includes several charitable initiatives that deal with climate change, HIV drug access and economic development in poor areas.

The foundation, which has raised more than US$2 billion ($2.8b) since it formed, has received bipartisan support. And the organisation has recently received high marks from philanthropy watchdog organisations.

However, critics have complained that the foundation, and the Clintons' paid speaking careers, have provided additional avenues for foreign governments and other interests to gain entree to a powerful family. Some complained that Hillary Clinton, during her tenure as Secretary of State, was in a position to reward foundation donors and may have responded inappropriately to requests for assistance.