South Asia is battling torrential monsoon rains which have pounded the region for weeks, causing widespread flooding, killing more than 250 people so far.

At least 81 people have died in flood-prone Bangladesh, where almost one-third of the impoverished nation is under water in one of the worst deluges in recent years.

Since Nepal’s monsoon season began last month, landslides, flooding and lightning have killed at least 131 people and left 48 others missing as incessant rainfall since Sunday inundated parts of the southern plains.

In India’s northeastern state of Assam, the death toll since the start of July has passed 60, with nearly three million people displaced.

In India’s Bihar state, at least nine rivers swollen by heavy downpours in Nepal rose beyond their danger levels and inundated many villages.

Bangladesh officials have warned of an extended disaster.

“The flood has been going on for at least 20 days,” the deputy chief of Bangladesh’s Flood Forecasting and Warning Centre, Udoy Raihan, told AFP news agency, adding that flooding usually lasted two weeks.

“And it is likely [to] continue for another 10 days due to heavy rains in Bangladesh and India.”

The annual monsoon is critical for replenishing water supplies, but also wreaks havoc across vast swaths of South Asia, causing widespread death and damage.

Floods, landslides and lightning strikes between June and September kill hundreds every year in the densely populated region.