Interior Minister Ruslan Alkhanov, who was heading the operation, said his forces on Friday had surrounded a group of fighters thought to be allied to Rappani Khalilov and to Akhmed Avdorkhanov, a former aide to late rebel leader Aslan Maskhadov.

He said six rebels were killed in the operation, which was being conducted in the east near the border with the Russian region of Dagestan, Interfax reported.

Preliminary information indicated two police officers were killed and two were wounded during the offensive, the ITAR-Tass news agency reported, citing an unidentified Chechen Interior Ministry source.

The Kremlin sent troops into Chechnya in 1994 in an effort to crush its separatist leadership, but they withdrew after a devastating 20-month defeat that left the southern Russian region with de facto independence.

Russian forces returned in 1999 after what they said was a rebel incursion into a neighbouring province and apartment building explosions blamed on insurgents.