Since Thursday, torrential rains across the country have caused flooding, rising waters and landslides that have swept away entire villages and left many residents trapped in the rubble.

Most of the deaths, 317, were reported in Khyber Pakhtunkhwa province, where monsoon rains that are only expected to intensify in the days ahead drove flooding and landslides that collapsed houses.

More than 150 people are missing in hardest-hit Buner district, where at least 208 people were killed and "10 to 12 entire villages" were partially buried, officials told AFP.

"They could be trapped under the rubble of their homes or swept away by floodwaters," said Asfandyar Khattak, head of Khyber Pakhtunkhwa's Provincial Disaster Management Authority.

"Separately, in Shangla district, dozens of people are also reported missing," Khattak added.

"There is no electricity or mobile signal in Buner, as power lines and mobile towers were damaged," he added.

The spokesman for the province's rescue agency told AFP that around 2,000 rescue workers were involved across nine districts, where rain was still hampering efforts.

"The operation to rescue people trapped under debris is ongoing," said Bilal Ahmad Faizi.

"The chances of those buried under the debris surviving are very slim," he added.

AFP journalists in Buner saw half-buried vehicles and belongings lying strewn in the sludge, with mud covering houses and shops.

A grave digger, Qaiser Ali Shah, told AFP he dug 29 burial places in the last two days.

"I have also dug six graves for children. With each grave, it felt as though I was digging it for my own child," he told AFP.

"For the first time, my body simply refused to carry me through. That's why today I apologised and said I cannot do this work anymore."

Flooded roads hampered the movement of rescue vehicles, as a few villagers worked to cut fallen trees to clear the way after the water receded.

"Our belongings are scattered, ruined and are in bad shape," shopkeeper Noor Muhammad told AFP as he used a shovel to remove mud.

"The shops have been destroyed along with everything else. Even the little money people had has been washed away," he added.

The provincial government has declared the severely affected mountainous districts of Buner, Bajaur, Swat, Shangla, Mansehra and Battagram as disaster-hit areas.

"We were trapped in our homes and could not get out," another Buner resident, Syed Wahab Bacha, told AFP.

"Our entire poor community has been affected... This road was our only path, and it too has been washed away," he added.

- Mass funerals -

On Saturday, hundreds gathered for mass funerals, where bodies wrapped in blood-stained white shawls were laid out on the village ground.

Fallen trees and straw debris were scattered across nearby fields, while residents shovelled mud out of their homes.

Pakistan's meteorological department has forecast "torrential rains" with monsoon activity "likely to intensify" from Sunday onwards.

The monsoon season brings South Asia about three-quarters of its annual rainfall, vital for agriculture and food security, but also brings destruction.

"The intensity of this year's monsoon is around 50 to 60 percent more than last year," said Lieutenant General Inam Haider, chairman of the national disaster agency.

"Two to three more monsoon spells are expected until the first weeks of September," he told journalists in Islamabad.

Landslides and flash floods are common during the season, which usually begins in June and eases by the end of September.

The torrential rains that have pounded Pakistan since the start of the summer monsoon have killed more than 650 people, with more than 920 injured.

Pakistan is one of the world's most vulnerable countries to the effects of climate change and is contending with extreme weather events with increasing frequency.

Monsoon floods in 2022 submerged a third of the country and killed around 1,700 people.

Another villager in Buner told AFP on Saturday that residents had spent the night searching through the rubble of their former homes.

"The entire area is reeling from profound trauma," said 32-year-old schoolteacher Saifullah Khan.

"I helped retrieve the bodies of the children I taught. I keep wondering what kind of trial nature has imposed on these kids," he said.