Patna, Aug 28 : Terming Bihar floods as national calamity, Prime Minister Dr. Manmohan Singh on Thursday announced immediate release of Rs 1,000-crore as flood relief for the state.

The Prime Minister also announced immediate release of 1.25 lakh metric tonnes of foodgrains for the affected people.

Earlier in the day, Dr. Singh and the United Progressive Alliance (UPA) Chairperson Sonia Gandhi today undertook an aerial survey of Supaul, Saharsa, Araria and Madhepura districts.

They were accompanied by State Chief Minister Nitish Kumar, Railway Minister Lalu Prasad Yadav, Union Minister of State for Water Resource Jaiprakash Narain Yadav and BJP MP from Purnia Uday Singh and Araria MP Sukhdeo Paswan.

With the Kosi River continuing to unleash its fury in Bihar districts bordering Nepal, over 20 lakh people are bearing the brunt of floods.

The Army was called out to help the marooned people.

According to the Central Water Commission, the Kosi, Ganga, Ghaghra, Punpun and Burhi Gandak were flowing above the danger level at several places along their course.

The flood have affected 15 districts - Muzaffarpur, Patna, Katihar, Nalanda, West Champaran, Khagaria Sheikhpura, Purnia, Saran, Begusarai, Bhagalpur, Supaul, Saharsa, Madhepura and Araria.

Acres of human habitation and farmlands are submerged in the waters of the Kosi river that has caused havoc by breaking its embankments upstream in Nepal and changing course, affecting around 2.5 million people in six districts of the state.

About one lakh marooned people have been evacuated so far, bulk of them by government boats and many on their own. Four helicopters and 200 country boats are working overtime to ferry the men and material to safe destinations. (ANI)