Two men claiming to have a bomb hijacked a Turkish passenger plane on Saturday as it was heading from northern Cyprus to Istanbul, officials and passengers said. One official said the hijackers were Iranians protesting against the U.S.

Most of the 136 passengers aboard the Atlasjet Airlines plane escaped the aircraft after it landed at an airport on the Turkish Mediterranean coast. Security forces were trying to convince the hijackers to release the last five hostages left on board.

Salih Usar, the transportation ministry of the breakaway Turkish Cypriot state, said the two hijackers were Iranians and were protesting against the United States, Turkey's private NTV television reported. He didn't offer any more details.

Maj. Gen. Mehmet Eroz said in northern Cyprus that the two hijackers were university students, NTV television reported.

The hijackers demanded that the plane be diverted to Iran, but the pilots said they would have to refuel and landed the aircraft an hour after takeoff at Antalya airport in southwestern Turkey, said Tuncay Doganer, CEO of Atlasjet.

Most of the passengers were freed by the hijackers or managed to escape from the rear exit of the plane, passengers who left the aircraft told NTV.

At least two passengers claimed that the hijackers were members of Al Qaeda, but others said they had not heard the hijackers say that.

Maj. Gen. Mehmet Eroz said in northern Cyprus that the two hijackers were university students, NTV television reported. CNN-Turk television claimed that the hijackers were Iranians but authorities would not immediately confirm the report.

Doganer said some crew members and "a small number" of passengers were left on board. The governor's office in Antalya announced that four passengers and two crew members were left on the plane. Security forces were communicating with the hijackers to convince them to surrender and release the hostages.

Aydin Kiziltan, CEO of Worldfocus, which owns the plane and had leased it to Atlas-Jet, said the pilots had also left the aircraft to prevent the hijackers from forcing them to fly the plane. The pilots left the plane through the cockpit window under orders from security forces, aviation authorities said.

Doganer said some of the passengers were released by the hijackers and the others managed to escape on their own.

"A small number of passengers are still on the plane and security forces were trying to rescue them," Doganer told NTV. "I hope that the standoff will end in a short period of time."

Passengers said there were two hijackers on board. They spoke Arabic to each other.

Doganer would not reveal the identity or nationality of the hijackers.

Passenger Erhan Erkul told NTV that the hijackers ran toward the cockpit shortly after takeoff, tried to break down the door but failed.

"They claimed to have bombs," Erkul said.

A female passenger, who was not identified, said the hijackers allowed the crew to serve water to the passengers.

Passengers speaking to NTV and CNN-Turk said the hijackers promised not to harm the passengers. "We are Muslims," the passengers quoted one of the hijackers as saying.

The hijackers allowed one of the doors on the side of the plane to be opened for fresh air after the air conditioner of the plane was switched off and some passengers fainted.

There have been several hijackings of Turkish airplanes in recent years despite increased security measures at the airports. In most cases, the hijackers surrendered and the passengers were safely evacuated.