BEIJING, Aug. 5 (Xinhuanet) -- About 1,250 U.S. Marines who are training Afghanistan security forces will have to remain at the warfront almost a month longer in order to complete a mission military leaders say is a top priority, according to a senior military official.

    Defense Secretary Robert Gates has also authorized the deployment of up to 200 other troops to Afghanistan to support the Marines. That includes eight helicopter crews that could be shifted from Iraq if commanders decide.

    The senior military official spoke to The Associated Press on Monday on condition of anonymity because the formal announcement has not yet been made.

    The decision to hold the 2nd Battalion, 7th Regiment there longer is part of an effort to capitalize on the gains the Marines have made in the training mission, said the official. The extension means that the battalion would return home in late November.

    Gates' decision to send the other support forces comes after weeks of discussions by top military leaders. He authorized Army Lt. Gen. Martin E. Dempsey, who is temporarily in charge of U.S. Central Command, to shift up to eight helicopters and their crews from Iraq to Afghanistan — four Cobra attack aircraft and four MH-53 heavy lift helicopters.

    The remainder of the support forces being deployed are smaller units, including engineers, route clearance troops and explosive ordnance disposal teams. It was not clear Monday whether those support forces also would return home in late November, or if they would stay longer in Afghanistan.

    (Agencies)