A suicide bomber wearing a vest filled with explosives attacked Iraqi police recruits on Tuesday in former dictator Saddam Hussein's hometown of Tikrit, killing at least 42 and wounding over 100, officials said.

Ahmed Abdul-Jabbar, deputy governor of Salahuddin province, said the attack took place outside a police recruiting centre where Iraqi men were lining up with their documents, hoping to get a job.

Who else would it be but al Qaeda, who keep on slaughtering us, said Abdul-Jabbar. They are the terrorists.

A police source in the city, 150 km (95 miles) north of Baghdad, said the main hospital was overwhelmed. Mosques broadcast appeals for residents to donate blood.

The hospital theatre now is full of dead and wounded young people. Ambulances are still evacuating casualties, the police source said at the hospital, asking not to be identified.

A police spokesman said more than 300 people were standing in line at the time of the attack.

There were many killed and wounded. The place was full of dead and wounded guys, he said.

Overall violence in Iraq has fallen sharply since the peak in 2006/07 of the sectarian slaughter triggered after the 2003 U.S.-led invasion. But shootings and bombings remain a daily occurrence.

Salahuddin province, home to Saddam's family, continues to suffer frequent attacks by suspected Sunni Islamist insurgents opposed to the Shi'ite-led authorities in Baghdad. Tikrit is primarily Sunni.

Insurgents have stepped up their assaults on Iraqi police and troops since U.S. forces formally ended combat operations last August ahead of a full withdrawal this year.

A Salahuddin provincial council worker, Muhanad Abdulrahman, said he rushed out to a balcony when he heard there had been a bomb in the city centre.

I saw a police pick-up truck rush by piled high with wounded people, he said. Blood was dripping down the sides of the vehicle and the people in the back were covered in blood.