Prime Minister Bill English has been briefed on allegations in a new book about a New Zealand military operation in Afghanistan and says "there doesn't appear to be anything new" in the claims.

On his way to question time at Parliament this afternoon English told media he had received an initial briefing from officials about claims in Nicky Hager and Jon Stephenson's book Hit & Run.

He would receive further written advice and speak to Defence Force Chief Lieutenant General Tim Keating when he returned from a current trip to Iraq.

Keating has in an interview with the Herald strongly defended the SAS against the allegations.

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"What has become clear is they believe the inquiries that have already been conducted have covered the issues," English said.

"There doesn't appear to be anything new in these allegations and a lot of them are couched pretty conditionally even by the authors themselves."

English did not rule out an inquiry into the claims but said the case for one did not appear to be strong based on today's briefing.

He repeated that view when questioned by Green Party co-leader Metiria Turei and Labour Party leader Andrew Little in Parliament.

"There is no suggestion in the briefings I have seen or the inquiries that have already been covered that New Zealand defence personnel have done anything other than observe the rules of engagement in a professional manner," English said.

He would not directly answer questions about whether NZ asked for support from American helicopters for the 2010 raid. Hager and Stephenson alleged that US helicopter gunships may have killed civilians in the two Afghan villages targeted in the raid.

In response to a question by Little, English said he "could not comment in detail" about further allegations that SAS soldiers may have shot villagers. But he added that he had been assured the military had followed the rules of engagement.

The book alleges that the New Zealand Special Air Service (SAS) killed Afghan civilians including women and children during a coalition raid in 2010, and that there were grounds to suspect a war crime had been committed.

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Government and Defence Force officials have stood by their statements in 2011 that no civilians died at the hands of New Zealand troops.

The investigation by Nato and the International Security Assistance Force (ISAF) referred to by English found that a malfunctioning gun sight on a coalition helicopter resulted in errant shots hitting a building by mistake.

The error "may have resulted in civilian casualties", the investigators concluded at the time.

Asked if the NZDF would release the ISAF report, English said he hadn't asked that question.

"There will be no doubt issues of jurisdiction and whose report it is ... we'd have to get advice about that."

Past Defence Ministers have previously said they could not rule out civilian deaths at the hand of foreign troops, but that New Zealand troops were not responsible for inflicting civilian casualties or injuries.

The NZDF reiterated this in a statement Tuesday night, while saying that it did not undertake investigations into the actions of other nations.

"That was the role of the joint Afghan-ISAF investigation," the Defence Force said.

Asked if he was worried the Government had not received the full picture from military officials, English said he was not.

He also had not talked to former Defence Minister Wayne Mapp, who held the portfolio at the time of the raid. Mapp has not returned calls from the Herald.

Hager and Stephenson's book concludes with a call for an independent inquiry with full powers to question past and present military staff and access Government records.

Opposition parties backed that request today.

Labour leader Andrew Little said the allegations in Hit & Run were serious and could not be swept under the carpet.

"The Defence Force's reputation is at stake so the Government must provide a comprehensive response," Little said.

New Zealand First leader Winston Peters said the integrity of NZ troops had been challenged in the book, and that "these allegations cannot be left to stand without proper investigation".

"It is not good enough for the Prime Minister, Bill English, to say there has already been an inquiry by the Afghan government and Coalition forces.

"What New Zealand must do is appoint a respected and trustworthy individual who the public can have faith in, and get the inquiry under way immediately.

The inquiry could be held behind closed doors to allow SAS members to speak in confidence, Peters said.

Green Party co-leader Metiria Turei also backed Hager and Stephenson's call for an inquiry, saying National needed to "put politics aside" on the case.

"If there is nothing to hide, then there is nothing stopping Bill English from announcing a full, independent inquiry into these allegations today."