BAGHDAD, Iraq – Guerrillas attacked a joint American-Iraqi convoy in Mosul yesterday, killing two Iraqi National Guardsmen only a day after a similar attack in the restive northern city left three Guardsmen dead.

In Washington, the White House said the search for weapons of mass destruction in Iraq has quietly concluded without any evidence of the banned weapons that President Bush cited as justification for going to war against Iraq.

The Iraq Survey Group, made up of some 1,200 military and intelligence specialists and support staff, spent nearly two years searching military installations, factories, and laboratories whose equipment and products might be converted quickly to making weapons.

White House press secretary Scott McClellan said yesterday there no longer is an active search for weapons. “There may be a couple, a few people, that are focused on that,” but it has largely concluded, he said.

In Iraq, American forces detained six suspects in the January 4 slaying of the Baghdad regional governor and six of his bodyguards, the military announced yesterday. Two of those detained in an early morning raid Tuesday were directly involved in the attack, said Brigadier General Jeffery Hammond, assistant commander of the 1st Cavalry Division, which controls Baghdad.

Yesterday, in the city of Baqouba, northeast of Baghdad, gunmen shot and killed Jawad Ibrahim, an assistant to the mayor, as he was fixing his car, police said.

Violence persisted elsewhere in the country, particularly in Mosul. The northern city has become increasingly troublesome for the American military since an American offensive pushed insurgents from their former stronghold in Fallujah.

For the second day in a row, insurgents attacked an American-Iraqi convoy in Mosul. The car bombing yesterday killed two Iraqi National Guardsmen and wounded two others.

On Tuesday, insurgents hit a convoy by detonating a roadside bomb and firing from a mosque, killing three National Guardsmen. The troops were bringing heaters and other supplies to a school when they were attacked, the military said yesterday. No Americans were reported hurt.

In a separate clash yesterday, insurgents fired on an American patrol in southern Mosul, sparking a firefight that killed one attacker and injured another.

The attacks again raised questions about the January 30 election for a national assembly. Iraqi officials have suggested people in hostile areas will be able to vote elsewhere if their regions aren’t calm enough for the vote.

Many Sunni Muslim clerical leaders have said the vote should be delayed because of the poor security. Yet in Egypt, one of the world’s leading Sunni clerics urged all Iraqis yesterday to vote in the election.

“Iraq’s Sunni and Shiite communities should take part in the January 30 elections,” the head of Egypt’s revered Sunni Muslim Al-Azhar University, Grand Sheik Mohammed Sayed Tantawi, said in remarks carried by Egypt’s semiofficial Middle East News Agency.

Mr. Tantawi, who is appointed by the Egyptian government, said if Iraqis do not elect a responsible government, “catastrophes will continue taking place in Iraq.”

Also yesterday, a predominantly Sunni group announced it will withdraw from the elections because its leader was detained and its calls for postponing the voting have been ignored.