Iraqi officials say a roadside bomb targeting a security patrol has killed one policeman and a passer-by in western Baghdad.

An Iraqi policeman says the blast Sunday morning also wounded three people in the Sunni-dominated Amariyah neighborhood near the capital's airport. A medic at the al-Yarmouk hospital confirmed the casualties.

Both officials spoke on condition of anonymity because they were not authorized to release the information. Insurgents often attack security forces to highlight Iraq's continued vulnerability as U.S. troops prepare to leave at the end of the year.

Washington and Baghdad are discussing whether up to 10,000 U.S. troops should remain into 2012.