New Zealanders in Yemen are already being monitored, Prime Minister John Key said yesterday.
In a revelation on More FM breakfast radio, Mr Key justified changes to the Government Communications Security Bureau (GCSB) law by saying some people in New Zealand were being trained by al Qaeda in places such as Yemen.
In ''the real world'', powers to spy on civilians were necessary, he said.
Mr Key later said he had signed warrants to observe people from New Zealand in Yemen and knew who they were.
''There are very specific and unique examples where we know that there is a threat or a potential threat and we have to take those responsibilities seriously,'' he said.
''People have trained in New Zealand and gone off to those camps and that's just the way things are.''
Mr Key would not reveal how many people were involved, or give their names.
But he said some of them could be New Zealand citizens and they were already being monitored.
''There are small numbers of radicalised New Zealanders who have either gone over to those environments or returned. Some are offshore and some are in New Zealand.''
Labour leader David Shearer would not confirm whether he had been briefed about an al Qaeda presence in New Zealand, but said Mr Key was simply politicking to try to give the impression that the controversial GCSB Bill was required.
''I think it's yet another one of those episodes when John Key is in a hole.
"He brings out the weapons of mass distraction. Bringing up threats to national security like this - it's not the type of thing you'd usually expect the prime minister to raise on breakfast radio.''
University of Otago deputy director for peace and conflict studies Prof Richard Jackson added Mr Key's claims of people working with al Qaeda were likely ''exaggerated''.