Dozens of people have died in Nepal and a million have been affected in north-east India following heavy rains that triggered landslides and flooding across parts of south Asia.

More than 50 people have been confirmed dead and 30 more remain missing in Nepal, where rescue efforts have been hampered by continued bad weather, which has blocked key highways and destroyed phone lines.

Heavy monsoon rains also caused devastation in north-east India. In Assam state, officials said at least 14 people were killed and more than a million people had been affected by rising flood waters.

Hundreds of villages in Assam have been affected, with some low-lying areas submerged in up to 2.2 metres of water, said Ravindranath, founder of the Rural Volunteers Centre and NGO.

“It might get worse, it all depends on the precipitation model. The rain model is changing because of climate issues,” he said. “We can’t assume anything now.”

Floods and mudslides have also hit other northern and eastern Indian states, including Meghalaya, Sikkim, Mizoram and Bihar. In Mizoram, floods have submerged about 400 homes in the small town of Tlabung, police said.

In Nepal, where more than 10,000 people are thought to have been displaced from their homes, further flooding is expected across southern regions near main rivers. The country’s department of hydrology and meteorology urged people to monitor rising water levels and move to higher ground when needed.

Gopal Adhikari, chief district officer of Siraha, one of the most affected southern areas, said most areas were still submerged. “Affected people have been moved to nearby schools and houses,” said Adhikari. The exact numbers who had been forced to leave their homes was not known, he added.

Ajay Shah Shiwali, a resident of Janakpur, in southern Nepal, said rain had stopped for the moment and rescue efforts were under way. “The water level has subsided in Janakpur city but the level is pretty high in rural areas. We have been seeing helicopters rescuing people and they have been rehabilitated to two centres in Janakpur city.”

More than 1,100 people have been rescued from flooded areas in Nepal.

In Bangladesh, at least a dozen people, mostly farmers in rural areas, have reportedly been killed by lightning since Saturday, according to Associated Press. A Water Development Board official, Rabiul Islam, said about 40,000 people had been affected, with many of their homes submerged.

Aid agencies have warned of severe conditions facing the 900,000 Rohingya refugees who are living in camps in Cox’s Bazar, in southern Bangladesh. At least 10 people have died and thousands of shanty homes have been destroyed since April by monsoon rains, officials said. Thousands were displaced from the camps as a result of unrelenting monsoon rains and wind last week.