BAQUBA, Iraq (Reuters) - An explosion hit an Iraqi security patrol north of Baghdad Thursday, wounding at least 10 people in the latest strike by insurgents against those seen as collaborating with U.S. occupation forces.

The blast struck members of the Iraqi Civil Defense Force as they conducted an early morning patrol through the restive town of Baquba, 65 km (40 miles) north of the Iraqi capital, where repeated attacks on Iraqi forces have taken place recently.

Police said the blast was caused by a remotely detonated explosive device placed on a cart selling diesel fuel. Doctors said at least 10 people were injured, two of them seriously.

In Britain and the United States, officials faced deepening controversy over why they went to war against Saddam Hussein after the former chief weapons inspector said the belief that Iraq had weapons of mass destruction was wrong.

The Baquba blast is the latest in a string of attacks against Iraqi security forces operating in the town, which sits to the east of an area known as the ``Sunni triangle,'' the hotbed of the 10-month insurgency against the U.S.-led occupation.

Two weeks ago a suspected suicide bomber blew up his vehicle outside a police station in the town, killing several bystanders. Late last year, twin suicide bomb attacks on police stations in Baquba and a nearby town killed more than a dozen.

As U.S. and coalition forces have ratcheted up strikes against suspected insurgents in recent months, the guerrillas have increasingly targeted the Iraqi police, Civil Defense Force and other U.S.-backed security teams seen as a softer target.

Lieutenant General Ricardo Sanchez, the overall commander of U.S. forces in Iraq, told a briefing last week that while attacks against coalition forces were declining, there was a worrying increase in assaults on local security groups.

Since May 1 last year, when President Bush declared major combat over in Iraq, more than 300 Iraqi policemen have been killed in shootings, bombings or suicide attacks, according to Iraq's Interior Ministry.

WRONG ON WMD

In Washington, former chief weapons inspector David Kay told the U.S. Senate's Armed Services Committee that almost everyone had been misled as to the degree of the threat posed by Saddam and his suspected weapons of mass destruction.

``Let me begin by saying, we were almost all wrong, and I certainly include myself here,'' Kay said in his first public appearance on Capitol Hill since stepping down last week.

``I believe that the effort that has been directed to this point has been sufficiently intense that it is highly unlikely that there were large stockpiles of deployed militarized chemical and biological weapons there,'' he said Wednesday.

With U.S. presidential elections due in November, Democrats trying to unseat Republican President Bush are using evidence such as Kay's to try to make a case that the White House exaggerated intelligence to go to war -- waged to rid Iraq of what Washington said was an arsenal of banned weapons.

In Britain, Bush's staunchest ally in the war against Iraq, Tony Blair, cleared the second hurdle of his toughest week in power Wednesday when a judge said the prime minister bore no blame for the suicide of a top Iraq weapons expert.

Although the report by senior judge Lord Hutton for the most part exonerated Blair, it did not rule on the merits of the war and many Britons remain unconvinced of whether it was justified.

SUICIDE ATTACK

While leaders scrambled to justify the reasons for going to war, attacks in the country continue apace.

Wednesday, a suicide bomber blew up his vehicle outside a hotel in an upmarket Baghdad district, killing a South African contractor and two Iraqis and wounding at least 10 others.

The attack followed a string of deadly strikes on U.S. soldiers and other targets, and as controversy reverberated from Baghdad to Washington over Shi'ite demands for early elections to transfer power to Iraqis by June 30.

U.N. Secretary-General Kofi Annan said if Iraq was deemed safe he would send a team to Iraq to study the feasibility of early polls. An advance U.N. team arrived in Iraq Tuesday ahead of a possible mission, U.N. sources said.

Early elections have been demanded by Iraq's most revered Shi'ite cleric, Ayatollah Ali al-Sistani, who has challenged the U.S. plan for regional caucuses to pick a transitional assembly. He says Iraqis should pick their leaders in direct elections.