Annual US-Morocco war games, cancelled by Rabat over a Washington-backed plan for the UN's Western Sahara mission, have resumed on a smaller scale after a compromise was reached, the US embassy said Wednesday.

"The Moroccan government did ask us (in the past 48 hours) if we could resume African Lion," embassy spokesman Rodney Ford told AFP.

"Most of our forces had already redeployed. But some elements are still on the ground. So we are conducting modified limited military engagements," he said.

Aerial training, refuelling and workshops were among the resumed activities, he added.

The US army was to conduct the "African Lion 2013" joint military exercises with Morocco from April 7-27, involving 1,400 personnel from US Africa Command (AFRICOM) and 900 members of the Moroccan armed forces.

But it began withdrawing troops and equipment last week amid disagreement over a plan to broaden the Western Sahara peacekeeping force's mandate to include rights monitoring in the disputed territory and in Sahrawi refugee camps in Algeria.

The US proposal triggered a furious lobbying campaign by Morocco, which called off the war games in a clear sign of Rabat's displeasure.

Washington this week dropped its demand that rights monitoring be included in the mandate of the UN mission in the Western Sahara, diplomats said, with the resolution merely to encourage stronger efforts on human rights.

The Security Council resolution on the UN peacekeeping force is to be voted on Thursday.

Giving the force a rights monitoring role is something human rights groups and the pro-independence Polisario Front have been advocating for years in the face of repeated allegations of torture of Sahrawi activists by Moroccan forces.

Morocco annexed the former Spanish colony in the 1970s in a move never recognised by the international community, and proposes broad autonomy for the phosphate-rich region under its sovereignty.

But this is rejected by the Polisario, which insists on the right of Sahrawis to decide in a UN-monitored referendum whether or not they want independence.