Rescuers were struggling to retrieve bodies from debris after flash floods triggered by heavy monsoon rains across northern Pakistan killed at least 321 people in the past 48 hours, authorities said on Saturday.

The majority of deaths, 307, were reported in mountainous Khyber Pakhtunkhwa province, the Provincial Disaster Management Authority said.

Most were killed in flash floods and collapsing houses, with the dead including 15 women and 13 children. At least 23 others were injured.

The provincial rescue agency told AFP that around 2,000 rescue workers were engaged in recovering bodies from the debris and carrying out relief operations in nine affected districts where rain was still hampering efforts.

The meteorological department has issued a heavy rain alert for Pakistan's northwest for the next few hours, urging people to take "precautionary measures".

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

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

Syed Muhammad Tayyab Shah, a representative of the national disaster agency, told AFP that this year's monsoon season began earlier than usual and was expected to end later.

"The next 15 days... the intensity of the monsoon will further exacerbate," he said.

More than 320 people have been killed in the past 48 hours as heavy monsoon rains triggered devastating flash floods across northern Pakistan, AFP reported citing officials on Saturday.

Meanwhile, the meteorological department has issued a fresh warning for heavy rainfall in northwest Pakistan in the coming hours.

The National Disaster Management Authority (NDMA) confirmed that most of the fatalities—211 deaths—were recorded in the mountainous Khyber Pakhtunkhwa province.