ISPARTA, Turkey - A Turkish budget airliner crashed in the mountains near the town of Isparta in central Turkey on Friday, killing all 56 people on board, officials said.

"Rescue teams have reached the wreckage ... There are no survivors," AtlasJet Airline's chief executive, Tuncay Doganer, told a news conference. Officials said all on board appeared to have been Turkish.

The 165-seat MD 83 plane, manufactured by McDonnell Douglas, crashed in the early hours of Friday in mountains in the Isparta province of central Turkey. It had been flying from Istanbul with 49 passengers and seven crew.

It was not immediately clear what had caused the crash, which occurred 12 km (7.5 miles) from Isparta's Suleyman Demirel airport.

Doganer said weather conditions were not abnormal at the time of the crash and that he knew of no technical problems aboard the aircraft. The aircraft's black box should explain what happened, he said.

Turkey is now in the grip of winter with snow and fog common on higher ground across much of the country.

"No matter what measures you take plane accidents happen and we see that 80 to 85 percent are due to human error," said Transport Minister Binali Yildirim, adding regular inspections had been carried out on the plane.

Rescue workers reached the mountainous crash site after military helicopters spotted the wreckage of the airliner.

DEBRIS, BODIES

A reporter from state-run Anatolian news agency who arrived with a military helicopter said she saw bodies strewn around the area of the crash, with personal belongings scattered on the hillside along with debris.

Some dead passengers were still strapped to their seats.

Turkish television showed a large section of the plane, with emergency exits open, intact on the side of a forested hill. It appeared the front and back of the aircraft were smashed.

Anxious relatives arrived at Istanbul airport seeking news of the passengers.

The aircraft disappeared from radar screens shortly before it was due to land at Isparta, about 150 km (90 miles) north of the Mediterranean resort of Antalya.

The state Anatolian news agency said aviation authorities lost contact with the plane just after the pilot said he was preparing to land at Isparta.

"As the plane was approaching its descent, it sought permission to land and after receiving a positive reply from the tower, contact was lost," the agency quoted local deputy governor Tayyar Sasmaz as saying.

The aircraft was leased by Turkish-based World Focus Airlines to private AtlasJet, which operates 15 planes.