LONDON (AFP) - Top allies of the United States defended the legal basis for the US-led invasion of Iraq and their military role there after UN Secretary General Kofi Annan reignited the debate over its legitimacy.

The governments of Britain, Australia, Poland, Bulgaria and Japan -- which have supported the war by deploying combat or humanitarian troops of their own to Iraq -- insisted the war was backed by international law.

Though there was no UN resolution explicitly backing the 2003 invasion, the United States and its allies say it was justified because Iraqi dictator Saddam Hussein had failed to comply with previous resolutions requiring him to disarm.

However, in an interview Wednesday with the BBC, Annan said a green light was needed from the United Nations Security Council.

"From the (UN) charter point of view it was illegal," Annan said.

Since the 1990-1991 Gulf crisis, the Security Council adopted a number of resolutions requiring Baghdad to abandon its programs of weapons of mass destruction and long-range missiles in full cooperation with UN inspectors.

The last one was adopted in November 2002, when UN inspectors re-entered Iraq after a four-year hiatus, warning Baghdad of "serious consequences" if it was found to be in material breach of the earlier resolutions.

Annan, referring to the tense diplomatic build-up to the Iraq invasion, said that "it was up to the Security Council to approve or determine what those consequences should be."

Trade and Industry Secretary Patricia Hewitt said "we spelt out at the time our reasons for believing the conflict in Iraq was indeed lawful and why we believed it was necessary to uphold those UN resolutions."

Hewitt, whose government sent thousands of troops to Iraq for the invasion and has kept them there, conceded on BBC radio that there was disagreement between international lawyers over the war`s legality.

In Sydney, Australian Prime Minister John Howard not only rejected Annan`s remarks but slammed the United Nations as a "paralysed" body, incapable of acting on major crises, like the current one in Sudan`s Darfur region.

Howard was one of US President George W. Bush`s strongest supporters over the invasion. He is struggling for a fourth term and his political survival in an October 9 general election in which Iraq is a key issue.

The invasion was "entirely valid" legally based on experts in Australia and UN resolutions, Howard said.

Australia still has several hundred military personnel in Iraq. Howard has been accused of misleading the public over the reasons for going to war and on other issues.

In a statement in Warsaw, the Polish foreign ministry`s spokesman Boguslaw Majewski said the "decisions taken by the international community had legal bases."

In deploying 2,500 troops of its own to post-invasion Iraq, Poland "acted in line with the Polish constitution by referring to UN Security Council resolution 1441 of November 8, 2002," the spokesman said.

"The use of force against Iraq was also justified by two previous resolutions," those of 1990 and 1991, he said.

In Sofia, the Bulgarian foreign ministry spokesperson Guergana Grantcharova also cited previous resolutions as supporting the case for war. Bulgaria has nearly 500 troops in Iraq.

Grantcharova also said UN resolution 687 still applied. By calling for "all necessary means" to restore international peace, that resolution opened the way for the 1991 Gulf war to end Iraq`s occupation of Kuwait.

In Tokyo, Chief Cabinet Secretary Hiroyuki Hosoda, the government`s main spokesman, told reporters that Annan`s remarks were "unclear" and Japanese officials would make inquiries about "his real meaning."

Prime Minister Junichiro Koizumi has been one of the most vocal supporters of the Iraq invasion led by US and British troops, despite widespread objections from the general public in Japan.

After the invasion, Tokyo last December sent troops to Iraq on a non-combat, humanitarian mission, Japan`s first military deployment since World War II in a country where fighting was under way.

Separately, Foreign Minister Yoriko Kawaguchi insisted the invasion was justified by UN Security Council resolutions requiring Iraq to open up to weapons inspections in the buildup to war.

In The Hague, Iraq`s visiting interim president Ghazi al-Yawar dodged questions about the legitimacy of the war, saying Annan was an "honorable guy."