President Clinton, increasingly concerned about Russia's military offensive in Chechnya, will tell Russian President Boris Yeltsin when they meet here Thursday that the policy "is a dead end" that needs third-party mediation, a top administration official said tonight.

Clinton will join several European allies in criticizing the Russian bombardment of Chechnya, according to national security adviser Samuel R. "Sandy" Berger. The two-month-old Russian offensive has killed hundreds of civilians and forced an estimated 200,000 people to flee the breakaway southern region.

Yeltsin and Russian Prime Minister Vladimir Putin have recently rejected criticism of the military action, saying the conflict in Chechnya is a domestic matter. Russian forces moved into Chechnya in late September to put down separatist Islamic guerrillas that Moscow blames for cross-border incursions into the neighboring region of Ingushetia and for a series of bomb attacks on apartment buildings in Moscow and other Russian cities that killed almost 300 people.

In Moscow today, Russian Foreign Ministry spokesman Vladimir Rakhmanin told reporters that Thursday's European security summit in Istanbul should focus on wider European and global security issues and not on the crisis in Chechnya.

"Russia will not give in to any pressure," he said. "Such pressure on a sovereign state, especially Russia, would be entirely inappropriate."

Clinton is scheduled to meet with Yeltsin on Thursday, when leaders from more than 50 nations will attend a summit meeting of the Organization for Security and Cooperation in Europe (OSCE). Berger said Chechnya is not on the official agenda but is likely to occupy much of the discussion during the two-day meeting.

Berger said in an interview that Clinton plans to raise Chechnya even if Yeltsin attempts to deflect discussion of the conflict. The president has been criticizing the Russian policy, Berger said, and in recent days "it's gotten worse."

The administration recognizes Russia's right to combat terrorists, including Chechens suspected of the bomb attacks, Berger said. But the "imprecise" bombardment of Chechnya is causing "high [civilian] casualties," Berger said, adding that the Russian strategy "in our judgment is a dead end, and they need to find the appropriate interlocutors" to mediate a settlement.

Russian military forces have bombed Chechnya from the air, and launched artillery and missile strikes against Chechen towns and villages. Russian forces withdrew from Chechnya in 1996 following a disastrous two-year conflict that ended with the region's effective independence from Moscow.

Berger said the 54-nation OSCE, of which Russia is a member, could play a mediating role in settling the current crisis.

Berger acknowledged that the United States and its European allies have limited leverage over Russia in the matter. Financial sanctions against Russia, such as withholding International Monetary Fund loans, "would cause a crushing burden on Russia that would destabilize Russia. . . . We have to keep a sharp eye on our own interests," which don't include an unstable Russia, Berger said.

On his way to Istanbul from Ankara, the Turkish capital, Clinton today visited the U.S.-built Dogukisla tent city that is housing refugees from the August earthquake in northwestern Turkey that killed more than 17,000 people.

The president, accompanied by his wife Hillary Rodham Clinton and daughter Chelsea, vowed to send more U.S. military tents and look for ways to help Turkey's economy. After stopping at several tents at the camp, near the city of Izmit, Clinton told the residents: "We were very, very moved by having family contact with other families. And we could imagine what our lives would be like if such a thing were to happen to us."

Many of the tents, which sit atop pavement, have some comforts, including electric space heaters, refrigerators and television sets. One woman holding a baby told the Clintons that the biggest difficulty is "the hard days of winter. And the humidity in the tent. The heat makes a lot of humidity."

The United States has supplied 6,000 tents to the region, and will send more, as winter nights threaten to take a toll on people who can't return to their homes, Clinton said. The president also praised Greek rescue teams for promptly helping Turkish victims of the August quake and another temblor that struck the region last Friday, killing more than 500.