At least 40,000 people in Pakistani-controlled Kashmir (search) died in last week's earthquake, a Pakistani official said Sunday. That would raise the overall death toll in the disaster to more than 54,000.

The prime minister of Pakistan's part of Kashmir, Sikandar Hayat Khan (search), estimated the toll in his region could be much higher because relief workers have not yet reached many affected areas, said his spokesman, Abdul Khaliq Wasi.

"The death toll is not less than 40,000," Wasi said.

However, he added that officials in Kashmir had not counted all the bodies, and the 40,000 figure was "a closest estimate."

An additional 13,283 people have been confirmed dead in Pakistan's North West Frontier (search) Province, and India has reported 1,350 deaths in the part of divided Kashmir it controls.

Confirmation of a final death toll will be difficult because many bodies are buried beneath the rubble.

"The United Nations is still operating on the government's official numbers," said Andrew MacLeod, Humanitarian Affairs officer with the U.N. Coordination and Assessment Team. "There are regions that still have not been reached, and the death toll is not final."

Khan said earlier that the confirmed casualty toll from the earthquake was 39,422 dead and 65,038 injured.

Deteriorating weather is likely to cause more casualties among the cold and homeless survivors of the magnitude-7.6 earthquake that struck the area touching Pakistan, India and Afghanistan on Oct. 8, the military said.

"There are bound to be casualties because of bad weather. How much, I don't know," said Maj. Gen. Farooq Ahmed Khan, Pakistan's relief commissioner.

On Sunday, torrential downpours halted airborne quake relief efforts in Kashmir, where the Pakistani military said one of its relief helicopters crashed in bad weather, killing all six people aboard.