* Aviation official says plane suffered engine problems
* TV images show trail of wreckage, huge fire
* Crash site in remote northern region

At least 40 people died when a plane carrying 48 passengers crashed into a mountain in northern Pakistan on Wednesday and witnesses at the site of the flaming wreckage said there were unlikely to be any survivors.
The military said 40 bodies had been recovered and rescue efforts involved about 500 soldiers, doctors and paramedics. The bodies were shifted to the Ayub Medical Centre in nearby Abbottabad, about 20km away.
Junaid Jamshed, a well-known Pakistani pop star turned evangelical Muslim cleric, was among those feared dead, an airline official said.
Pakistan International Airlines (PIA) said its plane lost contact with the control tower en route to the capital, Islamabad, from the northern region of Chitral.
The airline said the plane crashed at 1642 local time in the Havelian area of Khyber-Pakhtunkhwa province, about 40km north of Islamabad. Chitral, where the flight originated, is a very popular tourist destination in Pakistan.
"All of the bodies are burned beyond recognition. The debris are scattered," Taj Muhammad Khan, a government official based in Havelian, told Reuters.
Khan, who was at the crash site, said witnesses told him "the aircraft has crashed in a mountainous area, and before it hit the ground it was on fire".
Pakistani television showed a trail of wreckage engulfed in flames on a mountain slope.
Irfan Elahi, the government's aviation secretary, told media the plane suffered engine problems but it was too early to determine the cause of the accident.
Three foreigners on board
PIA said the plane was carrying 48 people, including five crew members and a ground engineer. But Sohail Ahmed, a PIA official in Chitral, said there were 41 people on board.
The airline said two Austrian citizens and one Chinese citizen, all men, had been on board. The flight manifest showed three people on board with foreign names.
A local trader at the site of the crash said the fire was still burning nearly two hours after the crash.
"They are removing body parts," Nasim Gohar told Geo TV.
The military said it had sent in troops and helicopters.
"PIA is doing everything possible to help the families of passengers and crew members," the airline said in a statement.
Jamshed, a singer in one of Pakistan's first successful rock bands in the 1990s, abandoned his singing career to join the Tableeghi Jamaat group, which travels across Pakistan and abroad preaching about Islam.
In his last tweet, Jamshed posted pictures of a snow-capped mountain, calling Chitral "Heaven on Earth".
Plane crashes are not uncommon in Pakistan and safety standards are often criticised.
In recent years, media have reported on multiple near-misses as planes over-ran runways and engines caught fire.
In 2010, a passenger plane crashed in heavy rain near Islamabad, killing all 152 people on board. Two years later, a plane operated by a private Pakistani company, with 127 people on board, crashed near Islamabad. All on board were killed.
PIA has also suffered major disasters in the past.
In 1979 and 1992, PIA jets crashed in Jeddah, Saudi Arabia and Kathmandu, killing 156 and 167 people, respectively.
In 2006, a PIA plane crashed near the central city of Multan killing 45 people.
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