A Cypriot airliner crashed into a mountainous area north of Athens yesterday, killing all 121 people on board after apparently suffering a loss of cabin pressure or oxygen.

"The pilot has turned blue," a passenger said in a mobile text message to his cousin, according to Greek television. "Cousin farewell, we're freezing."

Greek TV station Alpha said the pilot told air traffic controllers the Helios Airways Boeing 737 was experiencing air conditioning problems before communication with the plane - flying at 35,000 feet en route from Larnaca in Cyprus to Prague via Athens - was lost.

Rescue workers said they did not expect to find survivors.

A Greek police spokesman said there were 115 passengers and six crew on board the flight, of which 59 adults and eight children were heading to Athens and 48 to Prague.

Wreckage was scattered widely about the mountainous area, 40 kilometres north of Athens and dense black smoke billowed from several small fires. Only the tail section, bearing the Helios logo, was recognisable among the debris.

"I saw many bodies scattered around, all of them wearing (oxygen) masks," one witness told Reuters.

Police said 35 fire trucks, eight fire-fighting planes and three helicopters were at the scene, along with 105 special rescue operations officers.

There were chaotic scenes at Larnaca airport where desperate relatives demanded Helios release the passenger list for the plane. Some chanted: "Helios are murderers".

Akrivos Tsolaki, head of the accident investigation committee, told reporters at the crash site the plane's two black boxes - voice and data recorders - had been located.

Airport officials in Cyprus said flight HCY522 left Larnaca at 9 a.m. and lost contact at 10.30 a.m.

Two Greek F-16 fighter jets were scrambled after the plane lost contact with the tower at Athens international airport.

One of the F-16 pilots reported that he could not see the captain in the cockpit and his co-pilot appeared to be slumped in his seat, a Defence Ministry official said.

The ministry said it suspected the plane's oxygen supply or pressurisation system may have malfunctioned. Greek Defence Ministry officials said 90 minutes elapsed between the alert first being raised at 10.30 a.m. and the plane crashing at 12.03 p.m.

A source said the F-16 pilots were being flown to Defence Ministry headquarters for debriefing. "Their testimony is crucial for the continuation of the investigation. They are the ones with the last visuals of the plane."

A senior government official said there were no signs of foul play. "But we are still investigating all possible scenarios," he said.

The crash was the worst airline disaster in Greek history.

A Helios spokesman in Larnaca said: "We have no information about any problem with the AC (air conditioning) system. This plane received maintenance as usual and left Cyprus without any problems."

Kieran Daly, editor of Air Transport Intelligence, said the cause of the crash was a "puzzle".

"There are very good procedures in place for dealing with a lack of oxygen. There are so many warning systems, the crew should have been aware there was a problem," he said.

"The passenger commenting that it was cold suggests there was no air circulating in the cabin at all or the cockpit."

A spokesman for the European Aviation Safety Agency, Daniel Holtgen, based in Cologne, Germany, said: "It is highly unlikely that the loss of cabin pressure alone would cause such an incident. There would have to be other contributing factors."

Greek Prime Minister Costas Karamanlis broke off his holiday on the Greek island of Tinos to return to Athens. In Larnaca, Cypriot President Tassos Papadopoulos said: "I express my deepest sorrow and grief for the loss of lives of our compatriots and on behalf of the government I express deepest sympathy to all the relatives. We are standing by them and offering our support." At the airport in Prague, where friends and relatives had been gathering to meet the flight, screens showing arrivals read simply "delayed".

Helios was Cyprus's first private carrier, established in 1999. It flies to Dublin, Sofia, Warsaw, Prague, Strasbourg and several British airports using a fleet of Boeing B737 aircraft. There have been problems reported involving Helios planes in the past. In December 2004, three passengers were taken to hospital after the plane lost cabin pressure and made an emergency landing at Larnaca.

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