In Saddam Hussein's hometown, Tikrit, some 300 U.S. soldiers swept through the city overnight, detaining 30 Iraqis - including a dozen suspected insurgents - in one of the biggest raids since the end of the American-led war to oust Saddam.

In Baghdad on Friday, rockets struck a hotel used by Western contract workers, shattering windows but causing no casualties.

Attacks on Shiite and Sunni Muslim mosques have increased in recent weeks, raising tensions between the two communities as they compete for influence in post-Saddam Iraq. An upsurge in sectarian violence could undermine U.S. efforts to put together a democratic government in Iraq, where the Shiite majority was oppressed for decades under Saddam's mainly Sunni regime.

The blast Friday went off near the Sadiq Mohammed mosque in Baqouba, a religiously mixed city 35 miles northeast of Baghdad in an area dominated by Sunnis.

Footage from Associated Press Television News showed men pulling sheets over two bodies lying in the street as women in black robes wailed. Wounded people wandered in a daze. One car was set ablaze and other blackened cars were covered with debris from the blast.

A police investigator said officers discovered a car bomb in front of another Shiite mosque 1½ miles away and that it appeared a coordinated attack. The investigator said the car was rigged with three artillery shells and 330 pounds of TNT but fault wiring prevented it from going off.

The explosion outside the Sadiq Mohammed mosque was caused by a gas cylinder rigged with an explosive, U.S. officials said. Hospital officials and the U.S. 4th Infantry Division, responsible for security in Baqouba, said five people were killed and 37 wounded. The 4th ID said the dead included the bomber.

There were conflicting reports about details of the attack. Master Sgt. Robert Cargie, of the 4th ID, said the attacker tried to gain entry to the mosque but was turned away, apparently by guards.

"He walked a short distance away and detonated an improvised explosive device attached to a propane tank, killing himself," Cargie said.

Businessman Raad Sadek, who built and owns the mosque, said his brother saw the cylinder leaning against the door of the mosque and, after becoming suspicious, moved it to the middle of the street, where there was a large crater.

Under Saddam's authoritarian rule, ethnic and religious divisions in Iraq were largely kept under check. Since Saddam's fall in April, religious leaders on both sides have tried to prevent an outbreak of tensions.

Still, violence has erupted. On Dec. 9, a Sunni mosque was bombed in Baghdad, killing three, in an attack that mosque officials blamed on Shiite extremists.

A bomb went off on Nov. 3 outside a holy Shiite shrine in the city of Karbala, killing three people and wounding 12. In the most serious attack, a car bomb killed at least 80 people, including Shiite leader Ayatollah Mohammed Baqir al-Hakim, at a Shiite shrine in the holy city of Najaf in August.

Shiites, who make up the majority of Iraq's 25 million people, are concentrated in the southern parts of the country.

The violence has appeared separate from the guerrilla campaign against U.S. troops, which has focused in the majority Sunni regions north and west of Baghdad. But sectarian attacks have also raised resentment against the Americans.

Some Iraqis blame the occupation for the lawlessness and chaos of post-Saddam Iraq - others accuse the Americans of trying to foment Sunni-Shiite disorder as a pretext for continued rule, despite U.S. denials.

"This attack aims at igniting sectarian disputes," said Salah Hassan in Baqouba. "This is a Jewish-American scheme to harm the Muslims praying in the mosques. It is impossible that a Muslim would do this."

In Tikrit, U.S. troops raided 20 homes and three shops, searching for 20 suspected guerrillas, in a raid launched hours after a Black Hawk medevac helicopter crashed Thursday near the town of Fallujah to the south, killing all nine soldiers aboard.

The troops detained 14 of the suspects on the list, along with 16 others connected to the wanted men.

U.S. soldiers jumped over courtyard walls and kicked open doors to homes, dragging males outside into the freezing cold night while women and children huddled in bedrooms inside. Other soldiers used sledge hammers to break padlocks off shopfront doors and search the premises.

"Why do you come here, what have we done?" asked the daughter of one man detained. "My father has done nothing."

Among the detained was a man suspected of planting and detonating a roadside bomb that killed Pfc. Analaura Esparza Gutierrez, 21, of Houston, on Oct. 1.

"We see this as a good sweep of the area," said Lt. Col. Steve Russell, commander of the Tikrit-based 1st Battalion, 22nd Infantry Regiment of the 4th Infantry Division.

Troops also seized items involved in bomb making, computers and a handful of weapons, including several Kalashnikov rifles, pistols and a submachine gun.

Tikrit has been the scene of persistent anti-U.S. attacks in recent weeks. Saddam was captured last month near the city, but the anti-U.S. insurgency - blamed on his supporters - has continued.

In Baghdad on Friday, attackers blasted shoulder-fired launchers at the Bourj al-Hayat hotel at 6 a.m., said hotel security chief Hamza Ali. Two rockets hit the hotel, and a third exploded in the empty hotel pool.

Gunmen on Thursday attacked a U.S. Army supply convoy outside Balad, 45 miles north of Baghdad, killing a contract truck driver and wounding two other contractors, the military said Friday, without specifying the victims' nationalities.

Also Thursday, an officer with the Iraqi Civil Defense Corps was shot and killed as he guarded a petrol station outsdie Tikrit, and a Kurd was assassinated amid ethnic tension in northern Kirkuk.