PRISTINA, Yugoslavia (AP) _ An advance contingent of Russian troops flew into Kosovo on Saturday to help reopen a strategic airport and join an uneasy alliance with NATO peacekeepers struggling to rein in widespread ethnic unrest.

As the Russians disembarked, there were more reports of looting in Pristina and ethnic Albanians burning or taking over Serb homes in the western town of Pec. A potentially explosive confrontation was defused in one northern town when an ethnic Albanian rebel leader stepped in at the last minute to urge calm.

An Ilyushin-76 jet carrying 21 paratroopers and 18 airport technicians touched down at Pristina's airport in the early afternoon, the first airplane to land in Kosovo since NATO began its peacekeeping mission two weeks ago. It was followed moments later by a French transport carrying equipment to help make the airport fully operational.

The Russians will join about 200 of their countrymen who seized Slatina Airport on June 12 after traveling overland from Bosnia, beating NATO into Kosovo by hours and forcing tough negotiations on Russia's role in the peacekeeping mission.

The Russian and French transports are the vanguard of a dozen flights _ half of them Russian and half NATO _ expected over the next 10 days. They will bring crews and equipment to make the airport fully operational for military and humanitarian flights.

In the southern town of Lipljane, British soldiers arrested a member of the Serbian Interior Ministry police accused of involvement in as many as 56 deaths in Kosovo, a British forces spokesman said Saturday.

British Lt. Col. Robin Hodges said the man, who was not identified, was not on a list of suspects indicted by the international war crimes tribunal in the Netherlands, but tribunal officials have been notified.

Hodges said the arrest was made based on the accounts of witnesses who claim to have seen some of the murders. He said the killings occurred over a period of time, but gave no other details.

On Saturday, British and Russian troops mingled on the tarmac at the airport in Pristina. A Russian flag and the flag of Russian airborne forces flew atop the terminal building, with a British flag off to one side.

``This is all part of bringing Kosovo back to normality and the better future that we all hope for all the people of Kosovo,'' said British Lt. Gen. Mike Jackson, the NATO commander in Kosovo.

Jackson said he and Col. Gen. Viktor Zavarzin, who led the Russians onto the airfield two weeks ago, ``have developed a very good relationship, which I look on as a model for the future.''

Russia plans to deploy about 3,600 peacekeepers alongside a NATO-led force that eventually will include 55,000 troops. The entire Russian force should be in place within 45 days, said Col. Gen. Leonid Ivashov, who is in charge of foreign relations for the Russian Defense Ministry.

They will join a peacekeeping mission that so far has been unable to curb mounting unrest. Ethnic Albanians have been seeking revenge for atrocities committed by Serb-led Yugoslav forces since President Slobodan Milosevic cracked down on Kosovo separatists in February 1998.

One flashpoint is the northern mining city of Kosovska Mitrovica, where Serbs and ethnic Albanians control separate parts of the town. A potential clash was averted at the last minute Saturday when the leader of the rebel Kosovo Liberation Army, Hashim Thaci, persuaded about 500 ethnic Albanians to call off a march into the Serb-held area.

``We want to solve our problems peacefully,'' Thaci said. He was accompanied by the U.N. special envoy for Kosovo, Sergio Vieira de Mello, who said the march ``would be a disaster'' if it proceeded.

In the western city of Pec, Serbs continued to flee. Smoke rose from piles of burning debris as refugees cleared out ransacked homes and moved in.

``It's not my home. It's another home,'' said Hajrie Bucolli, a returning ethnic Albanian refugee, as she laid claim to an abandoned Serb apartment. ``I feel bad. But they asked for it.''

A top cleric in the Serbian Orthodox Church, Metropolitan Amfilohije Radovic, toured villages near Pec to bolster the morale of Serbs remaining there, the private Beta news agency reported.

He found the Orthodox church in the village of Nako desecrated, with icons burned and windows smashed, Beta said. The village of Belo Polje was ablaze and Serb property was being systematically looted, it said. Only one Serb had elected to remain despite appeals by the metropolitan for him to leave.

Burning and looting continued unabated Saturday as ethnic Albanians targeted Serbs and other groups who purportedly cooperated with Yugoslav forces in the crackdown against them.

Late Saturday, ethnic Albanians set fire to two, three-story Pristina mansions owned by prominent members of the Gypsy community. The owners had fled before the fire.

A Serbian Orthodox monk in Pec, Jovan Culibrk, told Yugoslav media that elderly Serbs taking refuge in the city monastery needed medical care but they could not receive help because ethnic Albanians had seized the city hospital.

Beta reported that Serb professors at Pristina University fled Saturday in a convoy of 40 cars, two days after the bodies of three men were found in the basement of a university building.

In Pristina, looters who weren't confronted by British troops ran into other problems. On man was killed by a booby trap as he broke into an apartment, Hodges said. In another incident, one looter accidentally shot and killed one of his companions.

Late Friday, gunmen opened fire on a U.S. Marine outpost near the center of Gnjilane in southeastern Kosovo. The Marines returned fire and called for reinforcements, who found one wounded gunman nearby. He later died, according to the U.S. European Command.

It was the second sniper attack this week against the Marines, who killed one Serb and wounded two others in a gun battle Wednesday.