Dark web hackers threaten to reveal 'dirt' on Donald Trump before US election

A group of cyber-extortionists claims to have dirt on US President Donald Trump, and will leak the information in time for the election.

The cyber-extortionists who stole a trove of private data from US entertainment law firm now have a new target in their sights: President Donald Trump.

In a blog post on Thursday US time on the dark web viewed by Variety, the hacker collective that is holding thousands of the law firm Grubman Shire Meiselas & Sacks's documents hostage said Trump would be the next subject of a data dump, the unidentified ransomware attackers claimed.

"The next person we'll be publishing is Donald Trump," the blog post said.

"There's an election race going on, and we found a ton of dirty laundry on time."

The hackers added, "And to you voters, we can let you know that after such a publication, you certainly don't want to see him as president. Well, let's leave out the details. The deadline is one week."

Variety has reached out to the White House for comment.

In a statement provided to Variety through a rep, Grubman Shire Meiselas & Sacks said: "Our elections, our government and our personal information are under escalating attacks by foreign cybercriminals.

"Law firms are not immune from this malicious activity. Despite our substantial investment in state-of-the-art technology security, foreign cyberterrorists have hacked into our network and are demanding $US42 million (NZ$70m) as ransom. We are working directly with federal law enforcement and continue to work around the clock with the world's leading experts to address this situation."

The statement continued: "The leaking of our clients' documents is a despicable and illegal attack by these foreign cyberterrorists who make their living attempting to extort high-profile US companies, government entities, entertainers, politicians, and others."

According to the firm, other organisations and companies including HBO, Goldman Sachs and the Department of Defence have been victims of similar cyber attacks.

It isn't clear what info the hackers might have on Trump or how it pertains to Grubman Shire Meiselas & Sacks, which is not known to have represented Donald Trump in any legal matter.