The BBC's John Andrew reports on the latest hostage crisis

Telephone engineers Darren Hickey, Peter Kennedy, Rudi Petschi and New Zealander Stan Shaw are even said not to have registered their arrival with the Chechen authorities.

Granger Telecom's Chief Executive, Sir Ray Verth: "Extra precautions were taken"

Three of the men work for Surrey-based firm Granger Telecom and were contracted to install a communications infrastructure for Chechen Telecom and the Chechnya Government.

Peter Kennedy, the fourth man, is a former long term BT employee whose specialist skills in satellite links led him to Chechnya on a freelance, short-term contract.

On Sunday they were taken hostage by a group of around 20 armed men after a gun battle with their bodyguards.

Sir Ray Verth: 'devastated by the seizure'

The men's families said they had been shattered by the news.

Granger Telecom's boss, Sir Ray Verth, in a statement made on Monday lunchtime denied suggestions that he had ignored Foreign Office advice to pull the men out of the country.

"Precautions were taken," he said "including the provision of an armed force on the ground".

He also made it clear that the men were fully prepared for the conditions in Chechnya.

"Granger has operated for many years in those parts of the world where conditions are somewhat difficult and often the subject of warnings by the Foreign Office.

24 armed guards

"Massive security was provided by Chechen Telecom to ensure the safety of our people including the provision of secure premises and 24 armed guards."

He said that the three employees were well prepared for this kind of work.

"Stan Shaw, has worked for the company for three years, and Darren Hickey, 26 and Rudi Petschi, 42, joined the company about six months ago.

A Granger Telecom sign outside the Surrey-based firm

"All of them have visited Chechnya more than once on this project. Both Stan Shaw and Rudi Petschi have extensive experience of working under difficult conditions around the world."

A BT spokesman said that Mr Kennedy was also experienced at working in this kind of environment and had worked for a range of telecommunications companies in a number of countries including Russia.

Mr Kennedy was subject to the same security precautions as the Granger Telecom team and is said to have been aware of the most recent Foreign Office warnings.

He is said to have only been on a very short contract of about a week.

Foreign Office: Warnings were ignored

The Foreign Office has confirmed that repeated warnings were specifically given to Granger Telecom about the dangers of working in Chechnya.

A spokesman said: "The last time the company was briefed on the situation was in August."

Foreign Office Minister Derek Fatchett: "We have provided the right advice"

Foreign Office Minister Derek Fatchett added: "We have given all the appropriate warnings.

"We cannot stop British citizens failing to heed that advice and Granger Telecom did not take that advice."

He added no other UK companies were in similar circumstances.

Families 'devastated'

Mr Hickey's younger sister Deborah, 21, said she her whole family was "We are all devastated. We never expected this. He had been over there before and never said anything bad about it."

She said that no-one blamed Granger Telecom: "It's no-one's fault. Darren is old enough to make his own decision to go out there or not."

Mr Shaw's wife, Lily, 40, told the Daily Mail she was "beside herself with worry".

"Our four-year-old daughter Priscilla is really upset and has been crying for her daddy. She keeps asking God to bring her daddy back."

"I just hope he will come back safe and soon. It would be awful if he were held for a year like those other hostages. I don't know if I could cope."

House stormed

The kidnap began when about 20 men in camouflage uniforms attacked the men's house in the capital Grozny.

Bodyguards opened fire but could not stop the kidnap.

General Bargishev: Unaware of men's presence

One of the bodyguards and several of the attackers were said to have been injured but it is not known whether any of the engineers were hurt.

The head of a special police anti-kidnapping unit, General Shaid Bargishev, said that security forces knew the identity of those responsible.

A police unit was reported to be questioning staff at a hospital in the town of Urus Martan in south-central Chechnya, where one of the attackers was believed to have been treated for gunshot wounds.

The kidnapping comes just two weeks after two British aid workers, Camilla Carr and Jon James, were released by Chechen rebels after 14 months in captivity.