Two men, one with a suspected broken jaw, have been airlifted from the Antarctic's most remote research facility after an incident described as a "drunken Christmas punch-up".

The brawl happened at the US-operated Amundsen-Scott South Pole station, located at the heart of the frozen continent. The station, where staff carry out a range of scientific investigations from astrophysics to seismology, is currently being rebuilt in a £76m project.

After reports of the fight reached staff at McMurdo station, the headquarters of the US Antarctic Programme, which is located on Ross Island, a US Air Force Hercules was sent to pick up the injured man and the other worker.

They were flown back to McMurdo, but it was decided the man's injuries were too serious to be treated in Antarctica and he was taken on to Christchurch, New Zealand, accompanied by a nurse and a paramedic.

Many of the McMurdo staff had been expecting a day off for Christmas but support workers returned to work to deal with the rare emergency medical evacuation.

A spokeswoman at Christchurch Hospital said a man was admitted on Christmas Day and discharged the following day.

"There was an altercation between two people -- there's no indication of the cause or of the background between the two folks," said Peter West, spokesman for the National Science Foundation which manages the US Antarctic programme.

The injured man is an employee of Raytheon Polar Services, one of America's largest defence contractors. A company spokeswoman, Val Carroll, said an investigation into the incident would be held. She said it was company policy not to release names of the two men.

The other man involved in the incident has flown back to the United States.

Polar medivac flights are rare occurrences, one of the most dramatic being a midwinter flight in 1999 for a woman doctor who developed breast cancer and needed urgent treatment.

It is currently summer in Antarctica, with light snow falling and daytime temperatures hovering around freezing, making it relatively easy to fly back and forth to New Zealand.