Prime Minister Helen Clark has risked incurring the ire of the United States and Britain by saying the invasion of Iraq has made the world less safe from terrorism.

She said the world was not a safer place five years on from the 9/11 terrorist attacks on the United States.

The Prime Minister revisited her reasons for opposing New Zealand's involvement in the invasion which had deposed Saddam Hussein as ruler of Iraq.

"You will recall at the time of huge debate around the intervention in Iraq that one of the things I said was that my concern was that that intervention would make the world less safe from terrorism rather than more safe, and that Iraq was not a haven for terrorists prior to the war there," the Prime Minister said.

"It certainly is now."

But she said the intervention of a multinational force in the former al Qaeda stronghold of Afghanistan, in which New Zealand played a role, was "absolutely right".

New Zealand troops continue to serve in Afghanistan. A corps of engineers was sent to Iraq after the invasion to help in reconstruction, but just one New Zealand soldier remains in that country, working with the United Nations.

A large coalition force led by the United States and Britain remains stationed in Iraq. Both US President George W. Bush and British Prime Minister Tony Blair are facing increased criticism at home for their nation's continuing role in Iraqi affairs.

Helen Clark yesterday praised Mr Blair's Government but said his foreign policy had obviously been controversial.

"That's been their choice. We made other choices, but that's certainly caused a lot of pain for the British Government on a number of occasions."

In 2003 Helen Clark had to apologise to US President George W. Bush after suggesting the Iraq war would never have happened if his Democratic Party rival, Al Gore, had won the presidency.

Yesterday Helen Clark said 9/11 had opened up a new era because it had shown the ability of terrorists to strike at the very heart of the most powerful nation on earth.

"That is a very sobering thought."

Subsequent terror attacks had shown the importance of international action at all levels by all nations to combat terrorism.

"9/11 was an escalation, and there have been many other terrible events since.

"The international community has reacted, and New Zealand has been very keen to be seen to comply in full with all the international conventions and protocols."