A car bomb has exploded near a Shia place of worship in the Iraqi capital Baghdad, killing at least 33 people and wounding up to 55 others.

Wednesday's apparent sectarian attack took place in Baghdad's northwestern Kasra district.

Worshippers were leaving the mosque after evening prayers when the car bomb exploded, and as onlookers rushed to help the wounded, a suicide bomber blew himself up in their midst, Reuters news agency said.

Policemen reportedly saw a second man fumbling to detonate an explosive belt and managed to stop him, but an angry mob overcame them and stabbed him to death.

It was not immediately clear who carried out the attack, but al-Qaeda-linked Sunni Muslim groups have been regaining momentum and striking on a near daily basis this year.

About 800 Iraqis were killed in August, according to the UN, with more than a third of the deadly attacks

happening in Baghdad.

The bloodshed, 18 months after US troops withdrew from Iraq, has stirred concerns about a return to the sectarian slaughter between 2006 and 2007, when the monthly death toll sometimes topped 3,000.