Working on foot in cold conditions, search teams scoured the rugged Venezuelan Andes on Friday for a missing passenger plane thought to have crashed with 46 passengers on board in the high mountain region.

The twin-engined plane vanished, apparently in good weather, soon after taking off from the high-altitude city of Merida just before dusk on Thursday. It was headed for the capital Caracas roughly 300 miles (500 km) away.

Mountain villagers reported hearing a huge noise they thought could be a crash soon after the disappearance of flight 518, operated by local airline Santa Barbara, local civil defence official Gerardo Rojas said.

"We have information of a possible finding," said national civil defence chief Antonio Rivero, although he added the plane was still officially listed as missing. He said he had no information about the people on board.

Venezuela's civil aviation authority said the plane was carrying 43 passengers and three crew members. The passenger list included a well-known Venezuelan political analyst and relatives of a senior government official, authorities said.

Rescue teams in the craggy mountain region where the plane was thought to have come down hiked on foot at night in the an area where temperatures drop below freezing after dark.

The first search parties travelled toward the Paramo Mifafi valley, a chilly area in a region of some snow-capped peaks of up to 13,000 feet (4,000 meters) that is home to condors and hiking routes that make it popular with backpacker tourists.

Weather conditions and visibility were described as optimum at the time of take-off by one air rescue official. He said the difficult terrain meant helicopters would not be used in the search until first light.

Family members who had waited for their loved ones to arrive in Caracas received help from state psychologists to deal with anxiety.

The head of Santa Barbara, a small Venezuelan airline that covers domestic routes and has seven Merida flights a day, said the roughly 20-year-old plane was well maintained and had no record of technical problems.

The pilot had worked with the airline for eight years and received special training for flying in the Andes, Santa Barbara President Jorge Alvarez told television station Globovision.

"I have to believe the pilot was certainly both competent and well-suited" for the flight, he said.

Early editions of most Venezuelan newspapers splashed news of the missing plane on their front pages, with some reporting villagers saying they saw the aircraft crash.

The plane was an ATR 42-300, a turboprop aircraft built by French-Italian company ATR.

The ATR 42 series has been involved in at least 17 accidents since first flying in 1984, according to the Aviation Safety Network, a private air safety monitoring agency.

Thursday's was the second major incident involving a Venezuelan flight this year after a plane carrying 14 people, including eight Italians and one Swiss passenger, crashed into the sea close to a group of Venezuelan islands in January.