At least 24 people have died and millions of homes have been left underwater after floods hit northeast India and Bangladesh.
Both countries have asked the military to help deal with the extreme downpour, which officials say could intensify with further rains forecast for the weekend.
At least 15 people have been struck by lightning in Bangladesh since Friday, and four people have been killed in landslides, police officials said.
Floods in Bangladesh, described by a government expert as potentially the country’s worst since 2004, have been exacerbated by runoff from heavy rains on Indian mountains.
In the Indian state of Assam, at least nine people died in the floods and two million others saw their homes submerged by floodwaters, according to the national disaster management agency.
The Brahmaputra River, one of Asia’s largest, broke through its mud dykes, flooding 3,000 villages and farmlands in 28 of Assam’s 33 districts.
“The amount of rainfall has been unprecedented,” said Sanjay O’Neil, a weather station official in Assam’s capital Gauhati. “We are expecting moderate to heavy rains in several parts of Assam until Sunday.”
Incessant rains have battered India for five consecutive days and led to the cancellation of several train services. Floodwaters submerged an entire railway station in Halfong, southern Assam, and dumped mud and silt along the railway tracks.
The Indian Army has been asked to help other disaster response agencies rescue those stranded and provide food and basic necessities to those whose homes are under water.
“We are using speedboats and inflatable rafts to rescue those affected by the floods,” an army official said.
Widespread flooding fueled by monsoon rains has stranded nearly 6 million people in the two countries.
In the lowlands of Bangladesh, districts close to the Indian border were the most affected.
According to the flood forecasting and warning center in Dhaka, the national capital, the water level of all major rivers in the country is rising. The flood-prone country has about 130 rivers.
Floods are expected to deteriorate in the worst affected districts of Sunamganj and Sylhet in the North Eastern region as well as Lalmonirhat, Kurigram, Nilphamari and Rangpur districts in northern Bangladesh, the center said.
Flights at Osmani International Airport in Sylhet were suspended for three days as floodwaters nearly reached the runway, airport manager Hafiz Ahmed said.
Bangladesh has a long and wet monsoon season and experiences tropical cyclones, generated in the warm waters of the Bay of Bengal.
But as human activity warms the planet, the South Asian country experiences hotter summers and higher rivers and more flooding during the monsoons – which are also less regular.
Disturbed weather conditions spell bad news for crop yields and disease. The WaterAid charity has warned that water contamination leads to a high risk of disease outbreaks.
“Water and sanitation facilities will be destroyed, washed away,” WaterAid acting country director Hossain I Adib said of “some of the worst flooding in decades”.
Drinking water will be contaminated by overflowing toilets and latrines, increasing the risk of disease outbreaks, he said, as he called for better access to clean water.
According to the UN climate science group, the IPCC, around 17% of people in Bangladesh are expected to be displaced over the next decade if global warming continues at the current rate due to rising sea levels.