He confirmed the Cabinet would today review New Zealand's commitment in Afghanistan, and that part of the review was whether the elite forces should be redeployed.
The SAS has been deployed in Afghanistan three times, the last in 2006, and the United States has asked for them to carry out another tour of duty in the counter-terrorism offensive.
"It could be today, it could be next week," Mr Key said when he was asked about a decision on TV One's Breakfast programme.
"More than likely today...there will be a review of our whole position in Afghanistan, what our commitment is and what our medium-term commitment should be."
Mr Key has previously indicated he favoured sending the SAS, saying he was sympathetic to arguments that more troops were needed to stabilise the strife-torn country.
New Zealand already has about 140 Defence Force personnel in Afghanistan.
They run a provincial reconstruction team operating in Bamiyan province, and have been there since 2003.
That commitment will continue to at least September 2010.
The Green Party has raised concerns in Parliament about the controversial handing over in 2002 of Afghan prisoners by New Zealand troops to US forces who allegedly mistreated them.
Mr Key said that was an issue that was being considered.
"New Zealand forces, on all the information I've had, have never been involved in the torture of people in Afghanistan," he said.
"They've handed people over (but) I think the rules have changed significantly."
