Terming the Bihar floods as a national calamity, Prime Minister Manmohan Singh [Images] has announced the immediate release of Rs 1,000-crore flood relief for Bihar.

During a visit to the flood-affected districts of the state along with United Progressive Alliance chairperson Sonia Gandhi [Images] and Home Minister Shivraj Patil [Images], Dr Singh also announced the immediate release of 1.25 lakh metric tonnes of foodgrain for the affected people.

Dr Singh, Gandhi and Patil also undertook an aerial survey of the flood-affected districts in an Indian Air Force helicopter.

Dr Singh is scheduled to review the relief and rescue measures at a high-level meeting with senior officials of the state government, before returning to Delhi [Images].

According to figures provided by the state's Disaster Management Department, approximately 19.78 lakh people from 725 villages in the districts of Madhepura, Araria, Supaul and Saharsa, have been affected by the floods.

Ten flood-related deaths have been reported so far with six deaths in Madhepura and four from Saharsa. But unconfirmed reports claim that the toll may be as high as 55.

The devastating floods were caused after Kosi  river, often called the 'Sorrow of Bihar',  changed its course last week due to a two-and-a-half kilometre breach in the Kosi barrage embankment, flooding villages, destroying crops and flattening houses in its way.