BAGHDAD - The Shiite-led government has demanded control over U.S.-funded Sunni groups that revolted against al-Qaida in Iraq in Diyala province by January — a move that could jeopardize fragile security gains in one of Iraq’s most turbulent areas.

The transfer, which was scheduled despite fears by the Americans that it’s too soon, will be a major test of the Iraqi leadership’s ability to overcome bitter rivalries between Sunnis and Shiites.