United Nations (PTI): UN Secretary-General Ban Ki-moon has expressed his sorrow over the destruction caused by the worst floods in five decades in the Indian state of Bihar and adjoining areas of Nepal.

Dozens of people have lost their lives and the death toll is still rising, following a breach in the eastern embankment of River Kosi, which straddles the India-Nepal border.

Extending "his deepest condolences to those affected, especially to the families of those who have been killed or who are missing," Ban said the United Nations is ready to assist as needed.

More than a quarter of a million homes have been destroyed, affecting nearly 3 million people in Bihar, one of India's poorest states, the UN Children's Fund (UNICEF) said.

Another 70,000 people have been uprooted in Nepal, where the displaced one third of whom are children are seeking refuge in schools, the agency reported.

"At a time like this, it matters little how the floods started or who or what is at fault. What is critical is urgent help to those in need," said Daniel Toole, UNICEF's Regional Director for South Asia.

He stressed that the agency's priority is to deliver urgently-needed supplies and ensure that children and women who are must vulnerable to disease receive medicine, clean water, sanitation and food.

"Even at best of times, South Asia has many of the poorest in the world," Toole stated. "These massive floods can wash away even the most basic hope that families have."

So far, UNICEF has delivered aid, including tarpaulin sheets, hygiene kits and water purification tablets, to 8,000 families in India and to over 10,000 people in Nepal.