An armada of rescue ships and helicopters scoured the chilly North Sea Thursday for 150 people missing after a fire engulfed an oil platform in possibly the worst oil rig disaster ever.

Occidental Petroleum Corp. the owner of the rig, said in a statement that a gas leak was apparently to blame. Derek Ellington, a survivor, described hearing a gas leak "screaming like a banshee" seconds before an explosion ripped through the Piper Alpha platform.Flames continued to leap into the air above the burning wreck of twisted metal. Two explosions triggered Wednesday night's inferno on the Piper Alpha rig, 120 miles off the Scottish coast.

Police said there was little hope of finding any more survivors.

Energy Secretary Cecil Parkinson told Parliament that 229 people had been on the oil platform. He said 65 survived and 16 bodies were found, leaving 148 missing. In addition, two of three rescuers who disappeared still were missing.

Police said most workers on the rig were Scottish, but Press Association, the domestic news agency, said workers from the United States, Canada, continental Europe and South Africa were aboard.

The rig is owned by Occidental Petroleum Corp. Officials at the company's Los Angeles headquarters had no immediate information on how many Americans were aboard the rig or on the cause of the explosion, said spokesman Peter Sinclair.

Armand Hammer, Occidental's chairman and chief executive officer, said in a statement: "I wish to extend my deepest personal sympathy to the families of the men who have been injured or who have lost their lives in this tragic accident in the North Sea. We will continue to do everything we can to assist the injured and their families."

If those missing are confirmed dead, the accident will be the world's worst oil rig disaster.

The Guinness Book of Records lists the worst as the capsizing of the Alexander L. Kielland platform in Norwegian waters in March 1980, when 123 people died.

"It was a case of fry and die or jump and try," said Ron Carey, 45, who managed to leap off the Piper Alpha into the 57-degree water after he was choked by smoke.

Towering flames lit up the night, and smoke blackened the sky Thursday.

"With the passage of time, hopes are fading of finding any other survivors," said a police statement.

Six NATO warships diverted from maneuvers to join the search that filled the skies with helicopters and the waters with more than two dozen boats.

Sleeping workers died when flames raced through the Piper Alpha's living quarters. Others leaped 150 feet into the water.

The Aberdeen coast guard said rescuers from a rescue vessel, the Sandhaven, disappeared into the flames as they headed to the rig in a small boat and a second explosion occurred. Police said two were missing.

Queen Elizabeth II sent a message of sympathy, and Prime Minister Margaret Thatcher expressed deep shock.

Aberdeen hospital spokesman Alan Reid told reporters 21 people were hospitalized, 13 of them in serious condition.