Russian forces on Thursday hoisted their flag over the key Chechen town of Urus-Martan after weeks of heavy fighting.

The Russian military says it has encircled the capital Grozny, and while it doesn_t plan to storm the heavily defended city, it has told civilians to leave by Saturday to avoid massive air and artillery strikes. President Clinton and other Western leaders have strongly protested the Russian ultimatum and criticized the overall offensive, which has produced large numbers of civilian casualties and driven more than 240,000 civilians from the territory. In Chechnya, the Russians and the militants battled for weeks in and around Urus-Martan, which is 12 miles southwest of Grozny and part of an important supply line for the rebels. About 300 militants were killed, and the rest retreated into the southern mountains of Chechnya, according to Maj. Gen. Vladimir Shamanov, the Russian commander. The Russians also claimed they had taken control of roads and crossing points south of Grozny, where the militants have been resisting in an attempt to keep supply lines open. The south of Chechnya is dominated by the Caucasus Mountains, and the rebels traditionally retreat to the hills when threatened by superior Russian firepower. Meanwhile, a top Russian military official reiterated that Russian forces would not storm the Chechen capital Grozny in spite of the military_s ultimatum. Still, the Russian army appeared to be tightening the noose around the capital. According to previous accounts, an estimated 6,000 militants and 15,000 to 40,000 civilians were holed up in Grozny. Many of the noncombatants are too ill or infirm to move. The Russian forces entered Chechnya in September, pursuing militants who had been driven back into the breakaway territory after invading neighboring Dagestan a month earlier.