WELLINGTON: New Zealand special forces involved in a Kabul office raid in which two Afghan security guards died acted in self-defence and followed proper protocols, the defence force said on Wednesday.

Afghanistan's government has accused international forces of going beyond their mandate in storming the building on December 24 after intelligence reports linked it to a plot to attack the United States embassy.

The NZ defence force (NZDF) confirmed New Zealand Special Air Service (SAS) troops took part in the operation, which the Afghan interior ministry described as "a heart-rending and tragic incident".

All 15 people captured in the raid were released that night on the intervention of an Afghan commander.

The Nato-led International Security Assistance Force (Isaf) organised the operation after receiving "advice of a credible threat to attack the US embassy", the NZDF said in a statement.

"Intelligence reports indicated there were two vehicles parked there that were thought to be loaded with explosives," it said.

It said the SAS troops identified themselves in Pashto and English when they approached the building but came under small-arms fire from security guards.

"The patrol was forced to act in self defence, killing two of the guards," it said.

The soldiers captured 15 people, including two who were injured and received treatment from a medic, the NZDF said.

It said an Afghan National Security Forces commander subsequently arrived and took command of the scene, personally vouching for the captives, who were released.

The NZDF said "a large number of weapons", including small arms, were found but did not list explosives among the items captured.

"Isaf has confirmed that proper protocols and rules of engagement were correctly followed," it said.

"Afghan authorities and Isaf are conducting an investigation. The NZDF will be closely following its progress."

Afghan interior ministry spokesman Zemerai Bashary said on Sunday that international troops exceeded their mandate in the raid.

"This was a heart-rending and tragic incident. The forces involved in that operation, regardless of the rules and pre-agreements, conducted an operation within Kabul city," he said.

He said an Afghan general with responsibility for some of the police involved in the raid had been suspended and a colonel had been fired over the incident.