BAGHDAD - A roadside bomb struck a police patrol northeast of the Iraqi capital, killing three officers, a police official said Thursday.

U.S. and Iraqi forces continued to be targeted by insurgents with regularity, raising concerns about the ability of Iraqis to keep the lid on violence once U.S. combat troops leave by Aug. 31, 2010.

The bomb targeted the patrol late Wednesday on the outskirts of the town of Jalula in the Diyala province, according to Maj. Ghalib al-Kharki, a police spokesman. Among the dead was a police colonel, he said.

Four officers were wounded in the blast.

The attack came the same day Prime Minister Nouri al-Maliki told a group of business leaders gathered in Baghdad that Iraq's budget was strained by the number of police and soldiers needed to protect the country.

Al-Maliki ordered security tightened in Iraq in August after nearly 100 people died in twin suicide truck bombings that targeted the finance and foreign ministries in central Baghdad.

He ordered the number of checkpoints increased and concrete blasts walls erected in areas where he had previously ordered them removed.