The Green Party is calling for an inquiry into war crimes allegations involving New Zealand troops in Afghanistan, before any decision is made about whether SAS forces should return to the country.
The Sunday Star Times newspaper claims the SAS may have broken the Geneva Convention when it handed Afghan prisoners over to American forces, without their names and dates of birth being recorded.
The prisoners were later mistreated.
Greens' Foreign Affairs spokesperson Keith Locke says there is also concern New Zealand troops knew the prisoners were likely to be mistreated.
He says an inquiry is necessary to determine exactly what happened in 2002.
Mr Locke says assurances from the US Government are not enough and until New Zealand can be guaranteed prisoners aren't being mistreated, SAS troops should not return to Afghanistan.
Defence Minister says NZ not guilty of war crimes
Defence Minister Wayne Mapp says New Zealand is not guilty of war crimes in Afghanistan, where the New Zealand SAS transported prisoners to a detention centre in Kandahar.
Mr Mapp says he believes the soldiers acted properly at the time and raised their concerns about the practice.
The SAS has been deployed to Afghanistan three times and the Government has been asked to send them back for another tour of duty.