BAGHDAD — The U.S. military captured two al-Qaida in Iraq bombing suspects and a Shiite militia leader in separate raids today north and south of Baghdad, the military said.

One of the men, arrested along with four aides, is believed to oversee security for al-Qaida's Iraq branch in Mosul — one of the terror network's last urban strongholds where U.S. and Iraqi forces have waged fierce battles against militants in recent months.

The man is also suspected of masterminding bombings targeting Iraqi police in the area, according to a U.S. military statement.

The other al-Qaida in Iraq suspect was captured along with an assistant in Tikrit, a Sunni Muslim city north of the capital. He allegedly facilitated suicide bombings and "foreign terrorist movement" for al-Qaida, the statement said.

The military said it also captured a suspected Shiite militia leader Tuesday south of Baghdad.

The U.S. refers to such fighters as members of Iranian-backed "special groups" who are defying a cease-fire order by anti-American cleric Muqtada al-Sadr. Many of them are believed to have fled recent fighting in Baghdad's Shiite militia stronghold of Sadr City.

The man and five associates surrendered without incident at his home in Kut, southeast of the Iraqi capital, a separate U.S. military statement said. He is accused of involvement in the murder of Iraqis and American soldiers, it said.

Witnesses in Mosul, meanwhile, said Kurdish troops reinforced positions Tuesday at Iraqi government buildings in the northern al-Arabi district, deploying fighters to rooftops despite an order from Prime Minister Nouri al-Maliki to vacate the area.

"We've seen an intensified presence of peshmerga (Kurdish militia), and their numbers have increased along with armored vehicles," one resident said on condition of anonymity out of fear of reprisals. He added that government troops had also increased their patrols.

The recent fighting in Mosul has been mainly to quash al-Qaida in Iraq militants, but the city also suffers from tension between Kurdish and Sunni Arab factions.

The discord stems largely from lopsided political representation in local government, which is dominated by Kurdish parties and their allies even though Arabs hold a slight majority in Mosul's province, Ninevah. Sunni Arabs boycotted the last provincial elections in 2005.

On Tuesday, Mosul's deputy governor, a Kurd who belongs to one of the two main Kurdish political parties in the area, denied any standoff the government forces.

"We are national political parties participating in the government and not fighting its forces," said deputy governor Khisro Koran. "We support the government and its security measures so that we are not excluded."