A road accident killed 16 people, mostly Iranian pilgrims, north of the Iraqi capital Baghdad overnight, the state news agency INA reported Saturday.

The "horrible accident" between Dujail and Samarra also injured 13 people, INA said, citing the toll from Khaled Burhan, director of health services in Salaheddine province.

He did not detail the circumstances of the crash but said most of the dead were Shiite Muslim pilgrims from Iran.

Almost exactly a year ago, on September 11, 11 Iranian Shiite pilgrims and their local driver died when their minibus collided with a truck in Babil province, south of Baghdad, a health official said at the time.

Millions of Shiite pilgrims, many of them from Iran, head each year to the holy shrine city of Karbala for Arbaeen, one of the world's biggest religious gatherings.

Arbaeen marks the end of the 40-day mourning period for the killing of Imam Hussein -- a founding figure in Shiite Islam and grandson of the Prophet Mohammed -- by the forces of the caliph Yazid in 680 AD.

More than 2.6 million pilgrims have flown into Iraq or crossed its land borders since Arbaeen began this year, according to figures issued on Friday by Iraq's interior ministry.

Road accidents are a recurring accompaniment to Arbaeen, which concludes September 6-7 this year.

Conflict, neglect and endemic corruption have left oil-rich Iraq's infrastructure, including roads and bridges, in disrepair. Officials also say speed, mobile phone use and driving while impaired contribute to crashes.

Last year in Iraq, road accidents claimed the lives of more than 4,900 people, an average of 13 per day, according to health ministry data.