PATNA, India - MORE than one million people have been trapped by floodwaters in eastern India after heavy monsoon showers caused a major river to shift its course, a minister said on Tuesday.

Massive rains in Bihar state caused the Kosi river to swell, breach its eastern bank and flow through a channel abandoned by the river hundreds of years ago.

Water levels in the new river, about one mile (1.6 kilometres) across, are not receding, Bihar Disaster Management Minister Nitish Mishra said, worrying flood control officials grappling with the challenge of sheltering two million homeless people.

'The marooned people have to be evacuated to safe places to save their lives after the shift in course in the Kosi river,' Mr Mishra said by telephone from Araria, one of the worst-hit districts bordering Nepal.

The force of the water was washing away about 150 metres (yards) of the protective levee every day and the breach is now about two kilometers wide, Mr Mishra said.

Bihar state Chief Minister Nitish Kumar, who visited the inundated areas, called the situation 'a catastrophe,' adding those trapped had found themselves in the way of the gushing torrents.

Thousands of people had been evacuated from Supaul, Araria and Madhepur districts to crowded relief camps, Mr Mishra said, adding hundreds more camps would have to be erected.

Those unable to find a place in the camps were living on highways untouched by the floods, atop government and high-rise buildings and in other shelters, he said.

At least 800 people have been killed in monsoon-related accidents following the heavy June-to-September rains across India, with Bihar accounting for 24 deaths since Saturday, a government spokesman said.

Bihar officials said the death toll could climb further as many areas were inaccessible.