UNITED NATIONS - The United States sought to use a UN resolution that would extend the UN peacekeeping mission in southern Sudan to press for the deployment of 20,000 UN troops in Darfur.

But the strategy is likely to face difficulties from Security Council members who want to keep two operations separate.

Meanwhile the United States and Britain have almost completed another proposal calling for sanctions against Sudan if the country doesn't agree to the UN force for Darfur.

The push for new sanctions was announced after a confidential UN report charged that Sudan's government has been flying arms and heavy military equipment into Darfur in violation of Security Council resolutions and is impeding peace efforts by using aircraft with UN markings.

The United Nations has 12,700 troops in southern Sudan, where they are monitoring a 2005 peace deal that ended a 21-year civil war between the mostly Muslim north and the Christian and animist south.

The UN chief has recommended extending the mission another six months, but on Monday the United States circulated a draft resolution that authorizes the troops to stay just three more months -- until July 31.

The U.S. proposal also expresses the council's intention to deploy 20,000 UN peacekeepers to reinforce the struggling African Union force in Darfur.

Poorly armed and funded, the 7,000 AU troops have been unable to calm the vast region convulsed by four years of fighting between rebels based in Darfur's ethnic African communities and nomadic Arab tribes backed by the national government.

At least 200,000 people have died and 2.5 million have been chased from their homes, and the conflict has spilled into neighboring Chad and Central African Republic.

After months of stalling, Sudan recently agreed to let the UN send 3,000 peacekeepers to Darfur, backed by six helicopter gunships. But Sudan has not yet approved a larger hybrid force for Darfur.

The draft resolution would also strongly back efforts by UN and AU envoys to get all rebel groups to sign the Darfur Peace Agreement, which has so far been signed only by the government and one rebel group. It would authorize UN assistance to implement the peace agreement.

The U.S. draft further expresses "grave concern" at the continued deterioration of the humanitarian situation in Darfur and "the increasing effects of the violence" in neighboring Chad and Central African Republic.

UN Secretary-General Ban Ki-moon has called on the Security Council to allow more time for diplomacy before considering whether to impose further economic and military sanctions on Sudan over the situation in Darfur.

Britain's UN Ambassador Emyr Jones Parry said the United States and Britain have drafted a new sanctions resolution which is "95 percent cooked" and are consulting other council members.

As for the north-south agreement, which ended a conflict in which some 2 million people died, the U.S. draft expresses "the intention to renew it for further periods" beyond July 31.

It also says the United Nations should put into place urgently the support packages for the African Union.

But South Africa's UN ambassador, Dumisani Kumalo, immediately objected, saying: "We can't mix everything in the same resolution." Russian Ambassador Vitaly Churkin agreed, saying: "At first glance there were some issues raised which do not have to be in the draft resolution."

Security Council members were also concerned that the United Nations had not appointed a representative for its Khartoum-based mission for southern Sudan since Dutchman Jan Pronk was expelled last November, diplomats said.