MOSCOW, Aug 19: At least 85 Russian soldiers were killed when their chopper crashed in Chechnya on Monday in an attack claimed by the Chechen rebels, which could prove to be one of the biggest losses to federal troops in the 35-month guerrilla war.

President Vladimir Putin, who launched the Chechen offensive in October 1999 while he was prime minister, called the incident a “catastrophe” and ordered a full-scale inquiry into the downing of the Mi-26’s helicopter.

Initial media reports said 117 people were on board the helicopter which went down just outside the main Russian military headquarters of Khankala on the eastern outskirts of the rebel capital Grozny.

“According to preliminary information, the helicopter went down after being hit either by a missile or heavy machine gun fire,” an unnamed military source told Interfax.

A Russian defence ministry spokesman quickly denied the chopper had been shot down by the rebels, insisting the crash was caused by an engine malfunction.

Appearing on Russian national television, he dismissed any Chechen involvement, which would prove a big blow to a Russian government that has repeatedly pronounced its military campaign there was all but over and won.

“The engine ignited when the helicopter was attempting to land,” Nikolai Deryabin told ORT television. “It was forced to make an emergency landing.”

But the rebels claimed responsibility for the attack in a statement published by the Kavkaz Center group on their Internet side. It said only that the incident occurred on Monday afternoon.

“According to preliminary information, tens of occupants who were in the helicopter were killed,” said the Chechen dispatch.

The Russian-made Mi-26, first built in 1983, is used mainly for heavy transport and can carry up to 20 tons of cargo and more than 100 equipped troops and armoured vehicles.

Roughly the size of a passenger jet, the helicopter can reach a top speed of 195 kilometres per hour (121 miles per hour). It is the heaviest military helicopter in the world.

Russian troops stormed into Chechnya in October 1999 in what Moscow termed an anti-terrorist operation that has since unravelled 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.—AFP