Baghdad ? British Prime Minister Tony Blair, who faces political troubles at home because of his crucial backing for the U.S.-led invasion of Iraq, made an unannounced trip to southern Iraq on Sunday to visit British troops and repeat his justification for going to war.

Blair told some of the 10,000 British soldiers in Iraq that the defeat of Iraqi leader Saddam Hussein was necessary in the wider campaigns against terrorism and the spread of weapons of mass destruction.

“This conflict here was a conflict of enormous importance because Iraq was a test case,” Blair said. “If we backed away from that, we would never be able to confront this threat in the other countries where it exists.”

While U.S. and allied forces in Iraq have so far failed to discover stores of chemical, biological and nuclear weapons despite months of searching, Blair has in no way softened the impassioned support for war that has made him an invaluable U.S. ally.

Blair’s daylong trip to Iraq was his second since the fall of Saddam’s government and followed President Bush’s surprise appearance in Baghdad on Thanksgiving. During Blair’s visit Sunday, he met in Basra with the top U.S. administrator of Iraq, Paul Bremer, who briefed him on political developments in Iraq and activities of the U.S.-led provisional administration.

Controversial presence

The occupation authority is beginning the unwieldy process of transferring sovereignty to an Iraqi government in time to meet a July 1 deadline.

The potential pitfalls in that process were underscored Sunday when U.S. military officials disclosed that soldiers in the northern city of Kirkuk had raided the offices of two Kurdish political parties that play an important role in supporting U.S. transition efforts.

Sgt. Robert Cargie said troops from the Army’s 4th Infantry Division raided the offices of the Kurdistan Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK) Saturday morning after receiving intelligence that they had violated restrictions on the possession of weapons. Cargie said soldiers found assault rifles, rocket-propelled grenades and rockets in the KDP offices, where they arrested a senior party member. Assault rifles and rocket-propelled grenades were found in the nearby PUK headquarters.

British Prime Minister Tony Blair meets troops as he arrives in Basra for a surprise visit to British soldiers in Iraq. Blair's visit Sunday was intended to reiterate his support for the coalition troops' presence in Iraq, a stance growing increasingly unpopular for him back home.

Kirkuk, an oil-rich city, has been tense since demonstrations Wednesday ended in gunfire, leaving five people dead. Iraqi authorities disagree over who fired the shots.

The violence erupted when hundreds of Arabs and ethnic Turkmens marched toward the PUK offices during a protest against the proposed creation of an autonomous Kurdish area in northern Iraq, with Kirkuk as its capital. The initiative is part of a plan being discussed by the U.S.-led occupation and the Iraqi Governing Council to establish a federal system in the country.

More violence

On Saturday, a demonstration in the southern city of Samawah also turned violent, prompting forces from the U.S.-led alliance to move into the streets and restore calm, according to Army Brig. Gen. Mark Kimmitt. As protesters rallied outside the local governor’s house, an unidentified gunman fired into the crowd and fled into a nearby building. Troops surrounded the building while Iraqi police arrested 20 to 30 suspects, Kimmitt said at a news conference Sunday.