UPDATED 9.23PM: Nicky Hager has accused the SAS of serious breaches of international law in Afghanistan, including potential war crimes.

His book Hit and Run, co-written with war reporter Jon Stephenson, has been launched in Wellington.

LISTEN ABOVE: Larry Williams talks to Senior NZ Herald reporter, David Fisher, who was at the launch.

Hager claims the SAS killed six civilians and wounded 15, during raids in Afghanistan.

It describes an SAS attack on two isolated villages in Afghanistan’s Baghlan province, seeking insurgents who attacked a New Zealand patrol in another province.

The book claims women and children were among the casualties, and the SAS and US forces burned and blew up about a dozen houses.

It also covers other operations, which Mr Hager and Mr Stephenson claim were tragic, disastrous and ill-conceived.

Speaking at the launch of the book this evening, Mr Hager said soldiers who were involved in the raids in 2010 have come forward with their stories, saying they believe they've been involved in war crimes.

Senior NZ Herald reporter David Fisher was at the launch and told Larry Williams the action was in response to an attack which claimed the life of Tim O'Donnell - the first New Zealander killed in Afghanistan.

"The premise of the book is that the raid for a number of civilian casualties is something that has been strenuously denied by a number of parties from Ministers of Defence, Prime Ministers, down to the New Zealand Defence Force itself."

Fisher said it's a very detailed account of what took place.

"It's been based on interviews with upwards of thirty people, twenty of those people in the military themselves, people who were disturbed or distressed by the events that took place."

Meanwhile,  the Defence Force says an investigation by the Afghan Government and the International Security Assistance Force in 2011 found allegations of civilian casualties were unfounded.

It says it doesn't investigate the actions of forces from other notices, but it's confident New Zealand personnel conducted themselves appropriately.

Defence Minister Gerry Brownlee is overseas and has been unavailable for comment.

The Prime Minister's Office is also saying little, other than they've not yet read the book.

And John Key, who was Prime Minister when the operation was approved, has made a brief comment, saying he's proud of the work the SAS did, and the support they provided in Afghanistan.

Mr Key has referred queries to Bill English's office.