The death toll from a string of bomb blasts targeting Shiite pilgrims on Wednesday in Baghdad rose to 36, while at least 138 others were injured, a local police source told Xinhua.

Six pilgrims were killed and 30 others injured when a roadside bomb went off in Yarmok district in western Baghdad, the source told Xinhua on condition of anonymity, adding nine others were wounded in another roadside bomb explosion in Haifa street in central Baghdad.

Earlier, two pilgrims were killed and 31 others injured in a blast in new Baghdad district, southeastern Baghdad, said the source.

The spate of attacks mainly against Shiite pilgrims in Baghdad began around sunset, the deadliest one was carried out by a suicide bomber who blew himself up among a large crowd of pilgrims who were marching on foot in Adamiyah district of northern Baghdad, killing 28 and wounding 68 others, said the source.

Iraqi police and emergency team sealed off the site immediately while ambulances rushed the wounded to the nearest hospitals, added the source.

Meanwhile, another explosive device planted in Altallya district in Baghdad was successfully defused.

The new string of attacks came a day after a series of mortar and bomb attacks that killed up to six Shiite pilgrims and wounded some 40 others as thousands of them were travelling on foot across Baghdad streets heading to a holy shrine in Kadhmiyah to observe the major Shiite ritual.

About 1 million pilgrims from many parts of Baghdad and other provinces are expected to gather near the Imam Mussa al-Kadhim shrine in Baghdad's northern district of Kadhmiyah for the annual commemoration of the death of the seventh of the most sacred 12 Shiite Imams.