Mumbai: The centre on Wednesday announced Rs1,000 crore in emergency funds and 1.25 lakh tonnes of foodgrains to Bihar as floods caused by the rising Kosi river inundated most of the state's eastern areas, leaving 55 dead and over 2.5 million homeless.

The 15 eastern districts bore the brunt of the flash floods, the worst in recent history, were the floods have affected nearly 2 million people.

Prime minister Manmohan Singh who undertook an areal survey of the flood-hit areas, has agreed to the state's demand for Rs1,000 crore in emergency funds and 1.25 lakh tonnes of foodgrains for distribution among the flood-hit.

The floods were caused by the turbulent Kosi, which breached the eastern afflux bund at Kusaha in Nepal and breached embankments bringing havoc to Bihar's Supaul, Araria and Madhepura districts.

The river also changed its course as it breached embankments, chief minister Nitish Kumar said, maintaining that the flood was not normal.

''As the course of the river has changed, the waters are likely to stay for some time,'' he said, adding that people in the are have been told to shift to safer places or relief camps set by the government.

The chief minister also asked the central government to ensure the supply of sufficient number of motorboats as also tents and other shelter materials to the state without any interruption.

Describing the floods in the state as a ''national calamity'', the prime minister promised all possible help to the state to tide over the situation.