Bombers killed around 40 people and wounded scores in several attacks in northern Iraq on Tuesday, days after the government vowed to expand a crackdown against militants in a region where al Qaeda retains influence.
In the worst attacks, two suicide bombers killed 27 people and wounded 68 when they blew themselves up outside an army recruitment centre in Baquba, 65 km (40 miles) northeast of Baghdad, an Iraqi security source said.
The U.S. military said 20 recruits were killed and 55 wounded, saying the attackers blew themselves up in a line of men outside the centre in Baquba, capital of Diyala province.
Sunni Islamist al Qaeda has sought to stoke tensions in Iraq's ethnically and religiously mixed northern cities, such as Diyala and Mosul, after military campaigns pushed its militants out of former strongholds in western Anbar province and Baghdad.
It has often targeted Iraqi forces and new recruits.
Iraqi security forces are poised to launch a major crackdown in Diyala, the Interior Ministry said on Sunday, the latest military operation aimed at stabilising the country.
A similar strike against al Qaeda in Mosul has helped cut violence there by half since it was launched in May, the U.S. military says.
The attack on the recruitment centre follows a string of bombings in Diyala province.
Hours after those attacks, three bomb blasts hit the northern city of Mosul, capital of Nineveh province.
In the worst attack, a suicide car bomber killed eight people and wounded a policeman at a police checkpoint, the U.S. military said. Police sources put the death toll at five.
Recent bombings could be al Qaeda's way of showing it is still a threat, despite improving security, U.S. officials say.
"What's happening here is the enemy knows the government and security forces are getting stronger," said Major Peggy Kageleiry, a spokeswoman for the U.S. military in northern Iraq.
