The Airblue Airbus 321 crashed into Margalla Hills that circle Islamabad to the north and west at around 10am amid thick fog and heavy rain.
Everyone on board was killed, making the crash the worst aviation accident on Pakistani soil.
Bin Yameen, deputy inspector general with the Islamabad police, said the operation to recover the remains of victims could not be resumed due to heavy rain. Difficulty in accessing the site was also complicating salvage efforts.
"We are waiting for the rain to stop," he said. "In such weather, neither helicopters can fly nor rescue workers move up easily. We may give it a try but it seems very difficult to carry out such operation in difficult terrain."
Even when the search is completed, identification of the victims could take several days, rescue workers scouring the twisted wreckage warned.
"There is nothing left, just piles and bundles of flesh," a rescue worker, Murtaza Khan, told Associated Press.
"There are just some belongings, like two or three travelling bags, some chequebooks, and I saw a picture of a young boy. Otherwise everything is burned."
The aircraft, arriving from Karachi, had been diverted from landing by the control tower. Investigators were trying to piece together what happened before it crashed into the hills, but the plane's black box data recorder has yet to be recovered.
The Pakistan Airline Pilot Association told AP the plane may have strayed off course, possibly because of the poor weather. Several officials noted that it seemed to be an unusual distance from the airport, about nine and a half miles away. "It should not have gone so far," said Air Vice-Marshal Riazul Haq, deputy chief of the Civil Aviation Authority.
The US embassy said at least two American citizens were on the plane, as the Pakistani government declared today a day of mourning for those lost in the crash.
Relatives of the victims gathered outside Islamabad's main hospital this morning, hoping to receive the bodies. Last night some scuffles broke out among relatives, hospital officials and police, as emotion and frustration over the lack of news ran high.
"What can the hospital do? It can't save anyone," said Surzamin Khan, whose 25-year-old son, Ansar, a captain in the Pakistan army, had been on board. "Life is in God's hands. It is he who gives and it is he who has taken it away."