Nine crack Russian troops died when a helicopter crashed to the ground outside a mountain village in Chechnya.

Chechen rebels said they shot it down, but Russian officials say the cause has yet to be ascertained.

The aircraft was bringing the troops back from what Itar-Tass described as a "special operation" on Thursday when it fell from the sky and burst into flames while coming into land at Engenoi, 60km (37.5 miles) south-west of Grozny.

The helicopter's crew survived and struggled to save the Interior Ministry troops inside.

Apart from the nine dead, another five men pulled from the wreckage are being treated for burns and other injuries.

Flight recorder

The flight recorder has been found and an investigation is under way.

A Chechen news website, Marsho, said rebels had shot down two helicopters in the last few days.

Russia launched what it describes as an anti-terrorist campaign against the rebels in October 1999 but has failed to stem daily guerrilla attacks.

Official estimates put the number of Russian casualties in Chechnya at 3,000 - a figure that is widely regarded as an under-estimate.

At the end of May, Chechen rebels killed a Russian pilot and injured two members of the Russian parliament in an attack on a helicopter over the neighbouring republic of Ingushetia.