At least 49 people were killed on Monday when a Bangladeshi airliner crashed in cloudy weather as it came in to land at the Nepalese capital's hill-ringed airport, officials said.

The chief executive officer of US-Bangla Airlines, Imran Asif, accused Kathmandu's air traffic control for giving wrong signals.

But airport general manager Raj Kumar Chettri said the pilot disregarded their messages and came in from the wrong direction.

Seventy-one people were on board the plane arriving from Dhaka when it clipped the fence at Kathmandu and burst into flames, Chettri said.

There were 33 Nepali passengers, 32 from Bangladesh, one from China and one from the Maldives.

"All of a sudden the plane shook violently and there was a loud bang," one of the survivors, Basanta Bohora, told the Kathmandu Post daily."I was seated near a window and was able to break out of the window."

The accident was the latest to hit mountainous Nepal, which has a poor record of air safety. Small aircraft ply an extensive domestic network and often run into trouble at remote airstrips.

"So far 49 people are dead and 22 are undergoing treatment at different hospitals," Sanjiv Gautam, executive director of the Civil Aviation Authority of Nepal (CAAN), told reporters.

Several people were rescued from the burning wreckage of the Bombardier Q400 series aircraft and are undergoing treatment at hospitals, army spokesman Gokul Bhandari said.

Chettri said that moments after the plane received permission to land, the pilot said he wanted to go in a northern direction. Asked by the control tower if there was a problem, he replied in the negative.

The plane was then seen making two rounds in a northeast direction, Chettri said. Traffic controllers again asked the pilot if things were OK, and he replied,"Yes".

The tower then told the pilot his alignment was not correct, but there was no reply, Chettri added.

"The plane should have come from the right direction," Chettri said, adding that it hit the airport fence, touched the ground and then caught fire.

It was not immediately clear if the pilot had issued a"Mayday" call, or distress signal.

US-Bangla Airlines' Asif, however, said that wrong signals might have led to the crash.

"A three-minute conversation between the pilot and the air traffic control before the landing indicated that they sent wrong signal to the pilot," he told reporters in Dhaka.

Series of Accidents

Many of the bodies that lay on the tarmac, covered with cloth, were charred, witnesses said. Thick plumes of smoke could be seen from the aircraft at the Tribhuvan International Airport.

Those on board include 12 Nepali tour agents who were returning after an annual sales conference in Bangladesh, an official said.

The aircraft that went down on Monday was 17 years old, data from tracking website Flightradar24.com showed. It descended to an airport altitude of 4,400 feet (1,341 m) and then climbed to 6,600 feet (2,012 m) before crashing about two minutes later, the website said.

Bombardier said on Twitter it was saddened by the accident.

"Our thoughts are with those injured, and their families," it said.

There have been a series of accidents at Kathmandu in the past.

In March 2014, a flock of birds shattered the windshield of a Malaysia Airlines MASM.KL jet as it landed in Kathmandu. The same month, a rear wheel of an Airbus A320 operated by an Indian budget airline caught fire after landing.

In 2012, a plane carrying trekkers to Mount Everest region hit a bird and crashed in Kathmandu, killing all on board.

In 1992, all 113 people aboard were killed when a Thai Airways flight from Bangkok crashed while trying to land in Kathmandu.

US-Bangla Airlines is a unit of the US-Bangla Group, a U.S. Bangladeshi joint venture company.

The two pilots and two cabin crew were Bangladeshi nationals, airline spokesman Kamrul Islam said in Dhaka.

"Our team will fly to Nepal as soon as the airport is open," he added."We are in touch with Nepali authorities."

The Bangladeshi carrier, which launched operations in July 2014 with a slogan -"Fly Fast-Fly Safe", operates Bombardier and Boeing aircraft.