Relatives grieve over the body of Mohammed Abdul Amir, 27, on Saturday at a morgue in Baqouba, capital of Iraq's troubled Diyala province, 35 miles northeast of Baghdad. Abdul Amir was killed Saturday by unknown gunmen in central Baqouba.

Baghdad ? Former Sunni insurgents asked the U.S. to stay away, then ambushed members of al-Qaida in Iraq, killing 18 in a battle that raged for hours north of Baghdad, an ex-insurgent leader and Iraqi police said Saturday.

The Islamic Army in Iraq sent advance word to Iraqi police requesting that U.S. helicopters keep out of the area because its fighters had no uniforms and were indistinguishable from al-Qaida, according to the police and a top Islamic Army leader known as Abu Ibrahim.

Abu Ibrahim told The Associated Press that his fighters killed 18 al-Qaida militants and captured 16 in the fight southeast of Samarra, a mostly Sunni city about 60 miles north of Baghdad.

“We found out that al-Qaida intended to attack us, so we ambushed them at 3 p.m. on Friday,” Abu Ibrahim said. He would not say whether any Islamic Army members were killed.

Much of the Islamic Army in Iraq, a major Sunni Arab insurgent group that includes former members of Saddam Hussein’s Baath Party, has joined the U.S.-led fight against al-Qaida in Iraq along with Sunni tribesmen and other former insurgents repelled by the terror group’s brutality and extremism.

An Iraqi police officer corroborated Abu Ibrahim’s account, but said policemen were not able to verify the number of bodies because the area was still too dangerous to enter.

Before the battle, the insurgent commander personally contacted Iraqi police in Samarra himself to tell them his plans, according to the officer and Abu Ibrahim himself. He asked that Iraqi authorities inform the American military about his plans, and requested that no U.S. troops interfere, they said.

The U.S. military said Saturday it had no record of U.S. troops ever being informed about the operation, and it was unclear whether Iraqi police followed through on Abu Ibrahim’s request.

The police officer said the al-Qaida captives would not be transferred to Iraqi police.

Instead, he said, he believed the Islamic Army would offer a prisoner swap for some of its members held by al-Qaida. The officer spoke on condition of anonymity because of the situation’s sensitivity.

Meanwhile, farther east, in Diyala province, members of another former insurgent group, the 1920s Revolution Brigades, launched a military-style operation Saturday against al-Qaida in Iraq there, the Iraqi Army said.

About 60 militants were captured and handed over to Iraqi soldiers, an Army officer said on condition of anonymity because he was not allowed to speak to media.

Afterward, hundreds of people paraded through the streets of Buhriz, about 35 miles north of Baghdad, witnesses said. Many danced and fired their guns into the air, shouting, “Down with al-Qaida!” and “Diyala is for all Iraqis!”

Like the Islamic Army, the 1920s Revolution Brigades includes former members of Saddam Hussein’s Baath Party and officers from his Army. Hundreds of 1920s members now work as scouts and gather intelligence for American soldiers in Diyala.

And at Baghdad’s most revered Sunni shrine, the Abu Hanifa mosque, voices blasted from loudspeakers Saturday urging residents to turn against al-Qaida: “We are your sons, the sons of the awakening, and we want to end the operations of al-Qaida … We call upon you not to be frightened, and to cooperate with us.”