Russian federal forces have killed up to 1,000 Chechen rebels in the past three to four days, a top Russian commander said Monday.

About 5,000 rebel fighters remain in the breakaway republic, but they can no longer mount organized resistance and only move around in small groups of 10-15 each, said Colonel General Gennady Troshev, deputy commander of the federal forces in the North Caucasus.

The Interfax news agency quoted Troshev as saying that federal troops also destroyed a rebel airdrome on frozen Lake Goluboye in Vedeno district near the border with the republic of Daghestan.

The airport was prepared to receive a light sports plane to evacuate rebel ringleaders Shamil Basayev and Khattab, Troshev said.

He denied recent reports that a group of Russian paratroopers was ambushed in southern Chechnya, but acknowledged that 31 federal servicemen died fighting back rebel attempts to break through encirclement.

Russian warplanes and helicopter gunships continued their raids on rebel positions in Chechnya, flying some 60 sorties Sunday and targeting the Argun and Vedeno Gorges.

In a related development, Major General Alexander Otrakovsky, commander of the group of marine units in Chechnya and chief of the Arctic Fleet coastal troops, died Monday of heart attack Monday in Vedeno, Interfax said.

Otrakovsky, 53, joined the federal campaign against rebels last September.