U.S. special envoy Richard C. Holbrooke, seeking a cease-fire between Serbian-led Yugoslav forces and ethnic Albanian separatists, crossed the front line today into rebel-held territory where he met for the first time with a commander of the separatist Kosovo Liberation Army.

With television cameras recording a scene that might well enrage Yugoslav President Slobodan Milosevic, the guerrilla commander wearing camouflage fatigues and carrying an automatic rifle warmly greeted Holbrooke at a barricade of farm machinery.

The guerrilla gave his name as Lum Haxhiu and led the U.S. delegation into Junik, a cluster of fortress-like farmhouses close to the mountains that mark the border between Albania and Kosovo, a province of Serbia, Yugoslavia's dominant republic.

Guerrillas manning a machine-gun nest guarded the village headquarters as Holbrooke, following Albanian custom, took off his shoes and sat cross-legged on thick rugs as Turkish coffee and spring water were served.

Holbrooke, nominated by President Clinton last week to be U.S. ambassador to the United Nations, said he was on a fact-finding mission and that the 30-minute conversation did not represent negotiations with the guerrilla group, which has been attacking Serbian targets in a campaign to win independence for Kosovo's ethnic Albanian majority. But the meeting signaled that the United States might be prepared to deal directly with the rebel group, which the Yugoslav government in Belgrade as well as some Clinton administration officials have condemned as a terrorist organization.

More than 300 people -- the majority of them ethnic Albanian civilians -- have been killed and perhaps 65,000 uprooted from their homes since Milosevic ordered a crackdown in late February on rebel village strongholds in Kosovo by the Yugoslav army and Serbian security forces.

U.S. diplomats are concerned that Ibrahim Rugova, their main negotiating partner among the Kosovo Albanians, has no control over the rebel group, a closely knit and highly secretive organization that totals at most just a few thousand fighters.

Rugova, elected president of the self-declared Republic of Kosovo, still commands wide respect among ethnic Albanians, but his nonviolent campaign for independence has been sidelined by the group, whose top leaders are believed to be based in Germany and Switzerland.

While the United States and its Western allies do not support independence for Kosovo, they are demanding that Milosevic restore the autonomy he stripped from the province nine years ago. Western powers fear the expanding conflict in Kosovo could spark a broader Balkan war.

"Events on the ground have been moving faster than the political process," Holbrooke told reporters, "but it's not too late to avoid a larger, general war. I'm not saying we are certain we will succeed, but we will give it our best shot."

Repeated threats of NATO intervention apparently have restrained Milosevic, but the guerrillas are striking back hard at government forces.

Holbrooke and his delegation were forced to take a long detour to the south along the border with Macedonia because of clashes on the main north-south highway out of Pristina, the capital of Kosovo. On Tuesday night, rebels seized the Belacevac open-cast coal mine, just five miles from the city, that feeds one of Serbia's biggest power stations. That area is where nine Serbs reportedly were kidnapped Monday.

Holbrooke will hold another round of talks Thursday with Milosevic in Belgrade, capital of both Serbia and Yugoslavia. Holbrooke said his immediate goal is a cease-fire, with roads reopened and with special police units, which have been attacking ethnic Albanian villages, withdrawn either to barracks or from Kosovo entirely.

Haxhiu, the guerrilla leader, described himself as being in charge of "morale, ethics and politics" in the Junik area. He gave Holbrooke a lecture on the rebels' determination to gain independence. With his beard and beret -- and reputation as an author -- diplomats quickly dubbed him the "poet-warrior."

"I hope that {Holbrooke's} visit will influence the U.S.A., and especially NATO, to stop Serbian aggression in Kosovo," Haxhiu told reporters. He welcomed Holbrooke's bid for peace but criticized him for not upholding "liberty" for Kosovo.

The international community has rejected the Kosovo Albanians' demands for independence, saying that redrawing borders in Yugoslavia would jeopardize the fragile peace in neighboring Bosnia and destabilize Macedonia, which has a large ethnic Albanian minority.

Holbrooke was accompanied by two U.S. ambassadors -- Chris Hill, who is leading the U.S. mediation mission, and Richard Miles -- as well as three members of Rugova's negotiating team. Just before their convoy of armored vehicles left Junik, several bursts of automatic gunfire could be heard in the distance as a Serbian police helicopter flew overhead.

Holbrooke, surveying the devastation of villages by Serbian security forces, drew comparisons to Bosnia during the early days of the 1992-95 war there but said that this time the international community is actively engaged in diplomacy backed by the threat of force. "NATO planning goes on and is getting more focused," Holbrooke said.

Diplomats said, however, that the likelihood of NATO intervening soon was receding as long as Milosevic prevented his security forces from pursuing operations in the area.

"I think the Serbs should get out of here and the original inhabitants come back and get help in rebuilding their homes," Holbrooke said.

Holbrooke was encouraged by Milosevic's permission for a six-nation Balkan "contact group" -- the United States, Britain, France, Germany, Italy and Russia -- to set up an observation mission in Kosovo. The group, which may number as many as 100 representatives, would mark the first sizable foreign involvement in Kosovo and could monitor a cease-fire. But Milosevic has rejected demands by the United States and its European allies to withdraw his special police forces until the rebels make a similar commitment. CAPTION: Meeting With Rebel: Envoy Richard C. Holbrooke meets a rebel of the Kosovo Liberation Army in Serbia's Kosovo province, signaling the United States may hold future talks with guerrillas to avert Balkan war. (Photo ran on page A01)