At least 40 people have been killed with 150 more missing in northern Afghanistan after flash floods ravaged an area northeast of the capital Kabul, officials said on Thursday.

A rescue operation was on to find the missing people after torrential rains overwhelmed Kamdesh district in Nuristan province -- about 200 kilometres (120 miles) northeast of Kabul.

"About 40 people were killed last night due to flash floods," Saeedullah Nuristani, head of the provincial council, told AFP.

He said 150 people were still missing and nearly 80 houses had been destroyed after floods swept through the area.

Saeed Momand, a spokesman for Nuristan's governor, gave a slightly higher death count, saying more than 60 people had been killed in the floods.

Torrential downpours and flash floods kill scores of people annually in Afghanistan.

Many poorly built homes -- mostly in rural areas -- are at risk of collapse during the rains in the impoverished country.

Dozens of people were killed last year after flash floods swept through swaths of Parwan province.

This year's flooding comes as Afghanistan has been rocked by a surge in fighting with the Taliban launching multiple offensives across the country.

The uptick in fighting also comes as Afghanistan is battling a third wave of Covid-19 that has overwhelmed the nation's ramshackle health care sector while other parts of the country have been hit by a punishing drought.