Prime Minister Vladimir Putin denied today that Russian tank fire had destroyed a bus carrying more than two dozen Chechen refugees, but the Reuters news agency said it has acquired video footage showing a gutted bus and bodies of victims apparently killed by an exploding shell.

Foreign Minister Igor Ivanov, meanwhile, told a European Union delegation that Russia needs no outside mediator to end the conflict in Chechnya, where Russian forces have launched a large-scale air and ground offensive to try to prevent separatist Chechen guerrillas from promoting rebellion in neighboring Russian regions. He said the Kremlin would talk to Chechen leaders who favor dialogue but that "terrorists" first had to be eradicated.

There was no evidence of the bus incident other than the videotape, which Reuters said it obtained from an amateur photographer in Ingushetia, a Russian region that borders Chechnya. If confirmed, the attack would represent the greatest loss of civilian life in a single incident since the Russian offensive began last week.

The photographer, who said he shot the film three days ago, told a Reuters television correspondent that a Russian tank had fired at the last of four buses in a refugee convoy as it was heading east from Grozny, the Chechen capital, to the border with the neighboring Russian region of Dagestan. He said 11 people aboard the bus were killed and 17 wounded. Tens of thousands of refugees have fled the region since the Russian attack began, most to Ingushetia and Dagestan.

Russian warplanes also have been attacking Chechen targets, and the Interfax news agency quoted Chechen officials today as saying that their ground forces had shot down another Russian aircraft, the fourth of the campaign. There was no word from Russian officials on the incident.