At least five people have been killed by a bomb blast at a Shia mosque in central Iraq.
Tensions are growing between Sunnis and Shias
The bomb went off as Friday prayers ended in Baquba, a largely Sunni Muslim town, about 65 kilometres (40 miles) north of Baghdad.
Dozens of people were hurt in the attack, medical sources said.
It came hours after US troops detained more than a dozen Iraqis suspected of targeting coalition forces, in a raid on Saddam Hussein's hometown of Tikrit.
Also on Friday morning, rockets hit a hotel in Baghdad used by foreign workers.
The Burj al-Hayat was hit by several rocket-propelled grenades, but no-one was hurt, hotel workers said.
Police in Baquba said the bomb went off at the end of the Friday prayer meeting.
"We had finished prayers and were shaking hands when I heard the sound of a large explosion," said Falah Hasan, a 43-year-old trader, who was injured.
"It happened close to me. Those next to me were killed."
Police said the blast was caused by a gas cylinder filled with explosives which was attached to a bicycle and left outside the Sadiq Mohammed mosque.
The explosion shattered windows and set fire to cars outside the mosque.
Television footage showed wailing women trying to cover body parts in the street near a blazing car.
There were scenes of confusion as worshippers flooded out of the mosque and people wandered dazed in the street.
Dozens of shoes, removed for prayers, were scattered across the bloodstained ground.
Doctor Sajed Abdallah, from Baquba general hospital, said about 20 of the injured required surgery.
"Some of them need legs or other limbs amputated," he said.
US forces are investigating the circumstances of the attack.
Tensions have been rising between the Shia majority in Iraq and the Sunni community favoured by Saddam Hussein, since the fall of the Baathist regime.
There has been a spate of attacks on mosques in Iraq in recent months.
Last August, more than 80 people, including a leading Shia cleric, were killed in a car bomb blast outside a mosque in the Shia holy city of Najaf.
Two months earlier, nine people died in an explosion near a mosque in the mainly Sunni town of Falluja, a centre of resistance to the US-led occupation forces and its supporters.