Rescuers raced on Monday to help tens of thousands of people in Myanmar who were stranded by rooftop-high floods, as the UN warned that swollen rivers threaten more areas and large swathes of Asia that have been hit by deadly monsoon rains.

Authorities in Myanmar said the death toll from flash floods and landslides caused by weeks of unrelenting rain rose to 46, with some 200,000 affected and villagers in remote areas forced to use canoes and makeshift rafts.

Hundreds have died in recent days in India, Nepal, Pakistan and Vietnam in floods and landslides triggered by a belt of heavy seasonal rains.