Two bombs exploded near Shi'ite pilgrims travelling through Iraq's capital Monday, killing at least 15 people and wounding 52 others, police and hospital sources said.

Thousands of Shi'ites are making the annual pilgrimage to the holy city of Kerbala for the Arbain religious rite amid Iraq's worst political crisis in a year after the Shi'ite-led government moved against two prominent Sunni politicians.

The crisis threatens to unravel Iraq's fragile coalition government of Shi'ite, Sunni and Kurdish factions and has raised fears of renewed sectarian violence.

The blasts struck the Bayaa district in southwestern Baghdad, where nine people were killed and at least 28 were wounded; and the northern Shaab district where the toll was six dead and 24 wounded, police and hospital sources said.

Pilgrims have been under attack for days in Iraq.

The explosion of two roadside bombs in southern Baghdad earlier in the day killed at least two people and wounded 12, while a sticky bomb attached to a bus carrying Afghan pilgrims blew up late Sunday, wounding nine.

Last Thursday bombings in mainly Shi'ite areas killed at least 73 people and wounded scores of others. The largest toll occurred at a police checkpoint near the southern city of Nassiriya where a suicide bomber killed 44 and wounded 81.

(Reporting by Kareem Raheem; Writing by Jim Loney; Editing by Matthew Jones)