"The appeal seeks 15.5 million dollars to cover the needs of at least 70,000 people over the next six months," said Elisabeth Byrs, spokeswoman for the UN's Office for the Coordination of Humanitarian Affairs.

The appeal is in addition to 102 million dollars already earmarked for Nepal for 2008 but which is to date only 44.5 percent covered, Byrs told journalists.

The Koshi River burst its banks in eastern Nepal on August 18, causing 80 percent of the river to change its course and leaving some flooded areas completely inaccessible.

Nepal has traded accusations with neighbouring India over who was to blame for the disaster.

Though the flood defences are 12 kilometres (7.5 miles) inside the Nepal border, India is responsible for their maintenance to protect its own population downstream.

Nepal says India failed in its duties, allowing the river to change course and empty huge volumes of water onto unsuspecting regions of India's northeast Bihar state.

About 60,000 people have been made homeless in Nepal, with up to five million affected in India, aid agencies say.