Iraq attacks on Shiite pilgrims kill 16

At least 16 people have been killed in a series of attacks in Baghdad despite heavy security across Iraq's capital.

A series of attacks targeting Shi'ite pilgrims have killed 16 people in Iraq despite heavy security. (AAP)

A series of bombings targeting Shi'ite pilgrims, including by a suicide attacker disguised as a woman, have killed 16 people in Baghdad.

The blasts are the latest in a protracted surge of nationwide bloodshed that has left more than 3600 people dead this year, fuelling fears Iraq is slipping back into the brutal communal bloodshed that blighted the country in 2006 and 2007.

Three blasts - two suicide bombings and a vehicle rigged with explosives - targeted pilgrims who were preparing for commemorations for a revered figure in Shiite Islam.

In the deadliest attack, a militant dressed in a black full-length woman's robe, or abaya, blew himself up amid a group of Shi'ite worshippers in the west Baghdad neighbourhood of Mansur.

The explosion killed at least eight people and wounded 26, according to a police colonel.

The worshippers - many from elsewhere in the country - were all walking from across the city to the district of Kadhimiyah, site of a shrine dedicated to Imam Musa Kadhim, the seventh of 12 revered imams in Shiite Islam.

The two-day rituals marking the anniversary of his death in 799 AD are due to climax on Saturday and Sunday and authorities have imposed heavy security measures on the capital, involving the closure of entire roads and barring certain vehicles from the streets.

Meanwhile, another suicide attacker detonated a car bomb in Baab al-Sharji, central Baghdad, killing three more, while a vehicle rigged with explosives in the northern neighbourhood of Urr left five dead.