A parked car bomb exploded a short time later in the Iraqi's capital's southern Abu Dsheer district, killing two people and wounding 10.

Iraq's police and army have ramped up security in the run-up to a major Shi'ite religious occasion that climaxes next week.

The first explosions occurred in quick succession in the al-Shurta al-Rabaa district of Baghdad, and one of the blasts struck near a Husseiniya, a place of worship for Shi'ites.

An Interior Ministry source put the toll at 23 dead and 107 wounded, but sources at three local hospitals said a total of 35 people had been killed, with another 80 wounded.

Iraqi security forces are on high alert in Baghdad, where Shi'ites, Iraq's majority community, have already started trekking through the streets for an annual pilgrimage to commemorate the death of Shi'ite holy man Imam Moussa al-Kadhim.

Shi'ite pilgrims have been frequent targets of a stubborn Sunni Islamist insurgency in recent years. Shi'ite religious rites were banned under Sunni dictator Saddam Hussein.

A series of attacks during the pilgrimage last year killed dozens of people and wounded hundreds. In 2005, rumours of a bombing on the Bridge of the Imams near the Imam Kadhim shrine in Baghdad touched off a stampede that killed 1,000 people.