Special report: Tension escalates in Iraq

   BAGHDAD, Dec. 25 (Xinhua) -- A suicide bomber struck a police checkpoint at the entrance to the University of Anbar in Ramadi City, some 110 km west of Baghdad, on Monday, killing three policemen and wounding three others, a local police source said.

   The attacker wore a belt laden with explosives, the source told Xinhua by telephone on condition of anonymity.

   In a separate incident, gunmen opened fire at an Iraqi army patrol in the al-Shuhadaa neighborhood in central Fallujah City, killing two soldiers and another aboard a military Humvee, the source said.

   Insurgents frequently attack U.S. forces and Iraqi security forces, accusing them of collaborating with U.S. occupation forces.