A suicide bomber killed 14 people on a bus in the northern Iraqi city of Mosul today, security sources said.
Another seven people were wounded.
Police in Mosul, 350 kilometres north of Baghdad, said the bus was carrying passengers to Syria. They said a wounded passenger had told them that the bomber boarded the bus and told the driver to change direction before detonating a belt packed with explosives.
The driver was among those killed, police said.
Iraqi and US security forces have launched a series of offensives in northern provinces this year, particularly in Mosul, which they have described as al-Qaeda's last major urban stronghold in Iraq.
Al-Qaeda, blamed for most large-scale attacks in Iraq, have regrouped in Iraq's north after being forced out of former strongholds in western Anbar province and around Baghdad during security crackdowns last year.
Attacks across Iraq have fallen 60 per cent since last June, US and Iraqi officials say, with the improved security credited to an extra 30,000 US troops and the growing use of mainly Sunni Arab neighborhood police units.
The neighborhood police units have spread across Iraq since Sunni Arab tribal sheikhs turned against al-Qaeda in Anbar in late 2006. The units have since become frequent targets for attack by al-Qaeda and other militants.