Four car bombs killed at least 25 people in Shi’ite Muslim districts of Baghdad on Monday, police said, in violence that coincided with a visit to the Iraqi capital by U.N. Secretary-General Ban Ki-moon.

Although no group claimed responsibility, the bombings appeared to be part of a relentless campaign by al Qaeda-linked Sunni Muslim militants to undermine Prime Minister Nuri al-Maliki’s Shi’ite-led government.

The deadliest attack occurred in the mainly Shi’ite neighborhood of Shaab in eastern Baghdad where a car bomb exploded in a commercial area, killing 11 people and wounding 28. […]