At least 33 people have died in floods and landslides triggered by heavy rains in Nepal and dozens more are missing, a government official said Wednesday.

Heavy monsoon rains have swelled rivers across the country, triggering floods and landslides that have destroyed homes.

Two children were killed when a school in the capital partially collapsed.

"Since Monday, 33 people have died and another 23 people are missing because of floods and landslides in several districts," home ministry deputy spokesman Jhanka Nath Dhakal told AFP.

Rescuers used helicopters and rubber boats to evacuate hundreds of people from affected villages.

"We are on high alert and our teams are working overnight in search and rescue operations," Dhakal said.

Scores of people die every year from flooding and landslides during the monsoon rains in Nepal and neighbouring India.

Millions of Nepalis are still living in tents or makeshift huts after a devastating earthquake last year that killed nearly 9,000 people.