Three bombs targeting Shia pilgrims in Baghdad have killed at least 29 people and wounded dozens more, Iraqi security and medical officials said. 

Thursday's attacks struck Mansur in west Baghdad, Baab al-Sharji in the centre of the city, and the neighbourhood of Shaab, as worshippers prepared to commemorate the death of a revered figure in Shia Islam, Imam Mousa al-Kadhim.

Shia pilgrims are often targeted by Sunni fighters who regard them as apostates, and in past years, multiple attacks have been carried out during the Imam Kadhim commemorations.

Due to the heightened threat of attack, the authorities had imposed heavy security measures involving the closure of entire roads in the capital.

The three bombings happened in the space of 30 minutes. The deadliest was in Baab al-Sharji, where a minibus approached a crowd of pilgrims and exploded, killing 14 people and wounding 17 others, according to police and medical sources.

"The suicide bomber... came speeding out from a side street towards a group of pilgrims on foot," said Police Captain Ahmed Nasir. "Many bodies were ripped to pieces."

A blast targeting Shias also went off in the town of Mishashda near Baghdad. 

At least 10 more people died elsewhere in Iraq on Thursday as gunmen and bombers attacked mostly police and military, Reuters news agency reported.

In the worst attack, gunmen broke into a house in the northern city of Mosul and killed a policeman, his brother and a cousin, a police officer said.

Also in Mosul, gunmen shot dead a female Shia ethnic Turkmen election candidate who had failed to get into parliament after last month's polls, police said.

Source: Al Jazeera and agencies