Iraq is considering multiple options regarding the future of the US military presence, ranging from a limited mission to no trainers whatsoever, a top official told AFP on Monday.

The remarks from Ali al-Alaak, the general secretary of the cabinet, come amid an apparent impasse between Washington's requirement of legal immunity for any US troops serving here beyond year-end, and a statement from Iraqi political leaders that there was "no need" for such protections.

"The US is insisting on that, and Iraq is insisting on not giving that,"Alaak said in an interview.

He said there were a variety of options being considered, adding that "there could be no training" at all.

Asked what he foresaw as the most likely scenario, Alaak said "there might be troops, but in very limited numbers."

US Defence Secretary Leon Panetta said on Thursday that any US forces remaining in Iraq beyond 2011, when all American troops must pull out under the terms of a bilateral security pact, would require legal immunity.

"Any kind of US presence demands that we protect and provide the appropriate immunity for our soldiers," he told a news conference in Brussels.

The Pentagon chief's comments exposed a potential sticking point over the legal status of American troops that could derail negotiations underway on a possible future US military force after the end of the year.

Following a two-hour meeting hosted by Iraqi President Jalal Talabani, leaders of the country's main political blocs said they agreed on the need for training of Iraqi forces and the purchase military equipment, according to a statement issued by government spokesman Ali al-Dabbagh.

But "the leaders agreed there is no need to give immunity for trainers."

The statement made no mention of how many trainers would be required, for how long or for what specific needs.

About 43,500 US troops remain in Iraq, and all of them must withdraw by the end of the year under the bilateral security accord, which remains in force if no post-2011 deal is agreed.