Police in the southern Russian republic of Ingushetia have discovered a mass grave believed to contain the bodies of 15 people arrested by Russian troops in neighbouring Chechnya several months ago.

The grave - on the Chechen-Ingush border - was reportedly found after relatives of the victims paid some Russian soldiers a large amount of cash for information.

The human rights group Memorial said seven of the bodies - of ethnic Chechen men who were uncovered last Friday - had been identified.

Correspondents say the discovery, which comes as the UN resumes activities in Chechnya, is a fresh blow to Moscow's human rights record.

Probe promise

Some of the bodies in the grave had plastic bags wrapped over their heads and showed signs of "violent death", according to the press service linked to Chechen leader Aslan Maskhadov.

Rights groups have often attacked Russia's tactics in Chechnya

A spokesman for the Kremlin office responsible for relations with Chechnya said Russian officials would not be making any comment on the report.

Mr Maskhadov's office said the 15 had been detained during "mopping-up" operations by Russian troops in north-western Chechnya in mid-May, although Memorial said the arrests began two weeks earlier.

Memorial said that in June military chiefs and prosecutors had promised to probe the detentions and begin inquiries for the release of the 15.

''But nothing happened after this promise,'' the group said.

An estimated 20,000 Chechen militants have been killed in the conflict

The news of the discovery comes two weeks after Russian intelligence released a video of a mass grave found in Chechnya that contained the remains of about 100 Russian soldiers and civilians - all reportedly beheaded.

The dead, believed to be victims of the first Chechen war from 1994 to 1996, were found in the village of Stariy Achkhoy, close to the alleged site of a death camp run by Chechen militants.

UN resumes

Russian troops stormed back into Chechnya in October 1999 in a self-declared anti-terrorist operation which has been repeatedly criticised as heavy-handed by human rights groups.

About 4,500 Russians have died in the conflict so far, according to official figures, although anti-war groups believe the actual toll may be three times higher.

Russian military officials estimate that 20,000 Chechen guerrillas have been killed.

The discovery of the mass grave came as the UN announced it was resuming aid operations in Chechnya halted in July after the abduction of Russian aid worker Nina Davydovich.