When asked if that meant New Zealand troops would effectively be doing the work of Hungarian troops, Mr Key said:
"New Zealand troops have always had the capacity to do that - and the question would be whether they [the Hungarian PRT] are fully exercising their responsibilities.''
"As far as I am aware the Hungarians don't go out at night - not in Afghanistan, they might in Budapest,'' he said.
Mr Key said he was comfortable with the suggested changes made by the New Zealand Chief of Defence Lieutenant General Rhys Jones.
"I wouldn't describe these as dramatic changes - but obviously we're doing the best we can to make sure our soldiers are as safe as possible and as fully resourced.
"The position in Bamiyan has been changing over the last three or four years. We've been advised that there has been more insurgent activity in that area for a few years now.''
He said it would not be be problem for existing New Zealand soldiers to patrol a wider radius in Afghanistan, but would not commit to increase the number of troops.
Earlier this year it was announced New Zealand troops would leave Afghanistan next year - this would remain that same and they would not return earlier.
Mr Key said there was currently no intention of sending the Special Air Service (SAS) back to Afghanistan.
"We always reserve the right to do that. But the advice is that it wouldn't serve New Zealand's interests well and it's not our intention to do that, but it can change,'' he said.
Mr Key defended having the New Zealand PRT in Afghanistan, saying it was there for the right reasons.
"The Labour Government committed New Zealand back in 2001 with the SAS, and again in 2003 into Bamiyan as part of the PRT.''
"It was a UN-mandated mission. There are a huge number of countries working alongside us and I think people need to cast their minds back to why all of these countries decided to go into Afghanistan - and that was to stop it being used as a base of terrorist activities,''
"No war is a good war,'' he said.
The New Zealand Government has received messages of support and condolence from Australian Prime Minister Julia Gillard and US Secretary of Defence Leon Panetta.
Flags on the Parliament forecourt were flying at half-mast today after the news of the deaths.