An Oxford University student and his family, who escaped death after being held hostage by Chechen rebels in a Moscow theatre, spoke of their relief that their ordeal was over.

Richard Low, and his parents Peter and Sidica, arrived at Heathrow Airport last night looking exhausted but "extremely happy" to be home.

Richard, a third year modern languages student at Lady Margaret Hall, and his mother were released after the 58-hour stand-off when Russian special forces pumped gas into the theatre, killing most of the Chechen rebels but also 118 hostages.

Peter Low, an advertising executive, was freed from the theatre on the second day of the siege after complaining of heart problems.

Richard was treated for the effects of the gas in hospital before being released and reunited with his family.

Speaking from the family's home in north London, Peter Low, 59, said he and his wife were pleased to be reunited with their 24-year-old daughter Louise.

He said: "We are extremely happy to be home and are looking forward to spending time with close friends and family.

"We would like to take this opportunity to thank Louise's boyfriend and her close friends who have supported her through every minute of our ordeal.

"We are immensely grateful for the efforts of everyone to secure our release, and on this day of national mourning in Russia we offer our sincerest condolences to the families who have lost loved ones.

"Our special thanks go to the British ambassador and all the staff at the British Embassy in Moscow for their hospitality and thoughtfulness during the past few days."

Prime Minister Tony Blair yesterday refused to criticise the Russian authorities over their decision to use gas when troops stormed the building to end the siege on Saturday morning.

The US embassy in Moscow says it has identified the gas used by Russian security forces as an opiate, a sleep-inducing substance which dulls the senses.