KATHMANDU - One person was killed and at least 25 others were missing in flash floods and landslides triggered by heavy rains that battered east Nepal, officials said on Sunday, the first known fatality since the annual rains began last week.

Heavy rains washed away a hydroelectric project under construction on the Hewa River in Sankhuwasabha district in eastern Nepal where 16 workers have gone missing, said Bimal Paudel, a government official.

"One body has been recovered while police are searching for the missing labourers," he said.

Nine people were also missing in flash floods and landslides in neighbouring Taplejung and Panchthar districts, bordering India in the east, officials said.

Gaurav Dhakal of the Panchthar district said overnight rains damaged two bridges on the Mechi highway, cutting off the road link to remote Taplejung district where four people were missing.

Officials said heavy rains prevented rescue workers from reaching the hilly Sidingwa village where at least 20 houses were at risk of being washed away.

Annual rains, which are crucial for crops, normally begin in mid-June and continue through September in Nepal.

Hundreds are killed or go missing in rains which spark floods inundating villages, crops and damaging infrastructure every year in mostly mountainous Nepal, nestled between China and India.

(Reporting by Gopal Sharma in Kathmandu; Editing by Rupam Jain and Lincoln Feast.)