The BBC's Robert Parsons: "Chechen president has promised an investigation"

Eyewitnesses say their severed heads were found on a highway together with personal documents, close to the border with the Russian region of Ingushetia.

The workers included three Britons and a New Zealander

The men were seized from their home in the Chechen capital, Grozny, in October in a spectacular attack mounted just a few hundred metres from Chechnya's special anti-hostage task force.

Russian President Boris Yeltsin was "deeply disturbed" by the beheadings, a Kremlin spokesman said.

Robert Parsons reports on "a gruesome end" to the kidnapping

And British Foreign Secretary Robin Cook called the murders "repugnant" and said efforts were underway to confirm the details of the case.

The Chechen President, Aslan Maskhadov, said one explanation for the killings might be that the Chechen government's anti-terrorist squad had been closing in on the kidnap gang and it might have panicked.

The bodies were found near the Ingushetia border

The remains of Britons Darren Hickey, Rudolf Petschi and Peter Kennedy were identified by the victims' former bodyguard.

The other victim has been identified as New Zealander Stanley Shaw.

The four men had arrived in the republic despite official warnings of the dangers to install a mobile telephone system.

Gun battle

Mr Hickey, Mr Petschi and Mr Shaw were employed by a Surrey-based firm, Granger Telecom.

Mr Kennedy was a former BT employee whose specialist skills in satellite links led him to Chechnya on a freelance, short-term contract.

They were taken hostage by a group of around 20 armed men, after a gun battle with their bodyguards.

After the kidnapping, the UK Foreign Office said the men and their employer had ignored warnings to avoid Chechnya.

However, Granger Telecom denied it had ignored the advice, and insisted it had provided adequate security for its employees.

The kidnapping came shortly after the release of British hostages Jon James and Camilla Carr, both aid workers who were held for over a year after being kidnapped in Chechnya.

Notorious for kidnappings

Chechnya has become notorious for kidnappings and other crime, but it is highly unusual for kidnap victims to be murdered.

Chechnya unilaterally declared independence from Russia in 1991. Russian troops failed to recapture the territory despite intense fighting with the rebels in 1994.

A 1996 ceasefire left Moscow with no effective authority over Chechnya, though it has not acknowledged the territory's independence.