BAGHDAD: Gunmen fired on Shiite pilgrims in Baghdad on Sunday, killing at least 20 and wounding 300, as worshippers gathered to mark the death of a revered imam, a senior health ministry official said.   

The attacks took place in several districts of central Baghdad, and insurgents also set fire to part of a medical college, health ministry departmental director Hakim al-Zamili said.  

In one incident, insurgents hiding in a Sunni cemetery ambushed a group of pilgrims who had been diverted by police from the capital's Al-Khilani neighbourhood to a highway taking them to the Musa Kadhim shrine, medics said.   

Gunfire and explosions could be heard echoing around the centre of the city from early Sunday as the pilgrims headed towards the mausoleum of Imam Musa Kadhim, where last year 965 Shiites died in a stampede triggered by attacks.