Relief workers are trying to reach millions of people displaced by unusually heavy monsoon rains in parts of India, Bangladesh and Nepal.

At least 20 million people have been affected by more than a week of incessant rain, with nearly 300 residents known to have been killed and vital crops washed away.

Relief supplies - such as clean water and food - have been slow to arrive, leaving millions at risk. Officials fear outbreaks of water-born diseases.

Northern India is among the worst hit areas with more than 150 people dead in Bihar, Uttar Pradesh states and northeastern Assam.

At least 50 people have died in Bangladesh with more than half of the country covered in floodwater.

In Nepal, swollen rivers flowing from the Himalayan Mountains burst their banks, flooding the southern Terai region. At least 84 people have been killed.

Monsoon rains cause flooding and deaths every year in South Asia but this year's rainfall has been exceptionally heavy.

Some information for this report was provided by AFP, AP and Reuters.