BAGHDAD (Reuters):

Gunmen ambushed an Iraqi police convoy north of Baghdad yesterday, killing 28 policemen, including the commander, and wounding 25 more, police said.

It was the second major ambush of police in the Baquba area in the past week - on Sunday, an assault on a convoy of buses near Baquba killed 13 Iraqi police recruits.

The campaign against Iraqi security forces highlights the challenge the Iraqi government faces in establishing an independent and powerful police force and army capable of taking over security from U.S. troops in violent areas.

The latest attack targeted police in a volatile town near Baquba, 65 km (40 miles) north of Baghdad, an area with a mixed population of Shi'ites and Sunni Arabs that has seen relentless sectarian bloodshed.