Albright, top, and Milutinovic, bottom, arrive at the peace talks RELATED VIDEO CNN's Brent Sadler reports Western powers hope for the best and plan for the worst Real 28K 80K Windows Media 28K 80K CNN's Christiane Amanpour reports that progress is being made. Real 28K 80K Windows Media 28K 80K

In this story: 'A lot of work to be done' Troop plan at heart of impasse NATO forces on alert RELATED STORIES, SITES

RAMBOUILLET, France (CNN) -- U.S. Secretary of State Madeleine Albright returned to the Kosovo peace talks to meet ethnic Albanian negotiators Sunday, hoping to convince them to accept a peace accord with no guarantee of independence for the rebellious province.

Meanwhile, Yugoslav President Slobodan Milosevic continues to oppose allowing a NATO peacekeeping force into Kosovo, which Western mediators say is a necessary part of any peace deal.

The peace talks resumed Sunday in Rambouillet, outside Paris, after the six-nation Contact Group agreed to extend a deadline to reach an accord from Saturday until 3 p.m. Paris time (1400 GMT, 9 a.m. EST) on Tuesday.

The draft agreement proposed by the Contact Group calls for giving Kosovo autonomy, but stops short of granting independence to the southern province of Serbia.

Ethnic Albanian leaders said Sunday they would seek to include a referendum on independence in any political settlement.

"Let me say that we always knew that these were going to be very difficult discussions," Albright said before meeting with the Albanian delegation. "There is a lot of work to be done."

Albright and British Foreign Secretary Robin Cook both made the case for Kosovo's ethnic Albanians to give up their demands for independence from Yugoslavia in return for guarantees of self-rule within Serbia.

NATO countries are threatening to launch airstrikes against Yugoslavia if the Serbs fail to go along with the peace plan, but Cook said the ethnic Albanians must agree to the plan before NATO could take action.

"If (the ethnic Albanians) don't sign up to these texts, it is extremely difficult to see how NATO could then take action against Belgrade," Cook told the British Broadcasting Corporation on Sunday.

The main sticking point to reaching a peace accord continues to be the opposition by Milosevic and Serb officials to any NATO peacekeeping force in Yugoslavia.

Serb President Milan Milutinovic said before negotiations began on Sunday that the Serbs would agree to a political settlement, but they want to see that pact separated from the question of a NATO force in Kosovo -- a demand Western diplomats say is non-negotiable.

"They told us bluntly, 'If you accept the troops the agreement will be perfect. If you don't, the agreement will be bad,'" Milutinovic said. "What is the point of this conference?"

Some 6,000 NATO troops are ready for prompt deployment to peacekeeping positions in Kosovo if an agreement is signed.

U.S. and Serbian officials said there were no plans for Albright to meet Serbian delegates on Sunday. A senior U.S. official said Washington did not expect the Serbs to agree to a complete peace deal including a NATO force in Kosovo.

Albright hinted she might leave the talks once she persuaded the ethnic Albanians to accept the deal on offer.

About 430 NATO strike and support planes are on alert for possible military action against Yugoslavia if the peace talks fail.

But at least one of the Contact Group nations, Russia, remains adamantly opposed to NATO military action.

On Saturday, Russian Prime Minister Yevgeny Primakov phoned British Prime Minister Tony Blair to say the potential for a diplomatic solution was far from exhausted, according the Interfax news agency.

State Department Correspondent Andrea Koppel Reuters contributed to this report.