TBILISI -- A group of about 250 Chechen rebels is readying itself on the Georgian border to enter the separatist Russian republic, sources close to the rebels in the Pankisi Gorge region bordering Chechnya said Saturday.

But Georgian authorities have disputed the figure, putting the number at no more than a few dozen rebels.

The Russian news agency Interfax quoted military sources as saying that 250 rebels under Chechen Commander Ruslan Gelayev were approaching the border with Russia, but were still some 10 to 20 kilometers (six to 12 miles) away.

Tension in Georgia's Pankisi Gorge, a lawless area on the border with Chechnya, has risen in recent days, with Tbilisi accusing the Russian Air Force of cross-border attacks on the area which have left two civilians dead.

Russia has rejected the accusation, but one attack on Friday, was confirmed by the Organization for Cooperation and Security in Europe (OSCE), a pan-European security body.

OSCE officials in Tbilisi said in a statement that observers had seen unidentified "objects" flying southwards in groups near the Russian-Georgian border and heard explosions a few minutes later.

Georgia has accused Russia of violating its airspace on five previous occasions in recent weeks.

Moscow believes Chechen rebels are using the Gorge as a rear-base to launch attacks on its forces in Chechnya and has accused Tbilisi of failing to crack down on the rebels.

Relations between the Russia and Georgia have been steadily deteriorating since a large group of Chechen rebels based in the Gorge launched an attack on Russian troops on July 27, killing eight border guards.

In a separate incident a Russian soldier and a policeman were killed and four other people injured in the Chechen capital of Grozny according to Russian police sources cited by Ria-Novosti agency.

It said unknown gunmen had opened fire on Russian forces that were carrying out a sweep of the Zavodski area of Grozny.

The agency said some of the gunmen were killed when the Russian forces returned fire, without giving more details.

Also in Grozny, a Chechen police lieutenant, who was working with the Russians, was shot dead while driving his car and his weapons were stolen, Interfax reported, quoting the Chechen Interior Ministry.

Ria-Novosti also reported that two armed rebels, who opened fire after being stopped for an identity check in northwest Chechnya, were killed by Russian forces.

The agency said quoting military sources that the rebel death toll in a "clean-up operation," launched in recent days by Russian forces near the town of Bamut near the Chechen-Ingushetia border had reached 25.

There is no way of checking the claims independently, AFP reported.

Russian troops stormed into Chechnya in October 1999 in what Moscow termed an anti-terrorist operation that has since unraveled into a brutal guerrilla war with daily casualties on both sides.

Russia has so far lost around 4,500 troops in the conflict, according to its own figures.