Russia's RIA news agency said today a group of 400 separatist rebels had attacked Chechnya'a second city, Gudermes, and a major battle was under way.
The agency quoted security service officers as saying the rebels were well armed, highly organised and appeared to have good knowledge of the city, just east of Chechnya's regional capital Grozny.
RIA quoted witnesses as saying trenches were being dug on the outskirts of the city. Officials in Grozny were put on alert, the agency said.
The defence ministry in Moscow said it could not immediately confirm the report.
Russia, which sent its forces back to separatist Chechnya in October 1999, says it controls the territory of the restive region on its southern fringes.
But Russian troops come under almost daily attacks and ambushes.
