PATNA, India, Aug 14 (Reuters) - Angry flood victims looted food from relief camps, assaulted officials and held them hostage in eastern India on Tuesday, as fresh rains brought more misery to tens of thousands of people in South Asia.

The death toll in eastern India rose to 83 and thousands more were marooned as rains lashed the region.

Authorities across South Asia, where nearly 800 people have drowned in the past month, or died from snakebites, hunger or water-borne infections, said they were struggling to keep diseases at bay.

In the impoverished Indian state of Bihar, hundreds of villagers clashed with police demanding more food in over a dozen places, officials and witnesses said.

Incidents of flood victims looting food and taking officials hostage until victims were given food and other supplies, were also reported.

"The fear of losing whatever little food we have has even robbed us of our sleep," villager Ram Uday Singh said at a relief camp in Bihar's Begusarai district.

Torrential rain triggered by a storm flooded new areas in the state, including its capital Patna, officials said.

A boat overturned in Khagaria district, drowning at least seven people.

In Kolkata, eastern India's biggest city, rain water continued to flood homes. At least 30 cases of chikungunya -- a viral fever caused by mosquitoes -- have been reported from the city, authorities said.

Health workers were clearing storm water and spraying insecticides in the congested city to kill mosquitoes.

"We are desperately trying to control an outbreak by increasing our vigil and undertaking preventive measures," state health services officer Sanchita Bakshi said.

HIGHWAY CUT OFF

In neighbouring Orissa, a highway connecting the mineral-rich state with the rest of the country was flooded. At least five people were swept away by surging rivers and hundreds of houses collapsed in overnight storms.

"We have not eaten anything for the last two days as the market is under water and our homes are gone," said R.K. Sahoo, a villager in Bhadrak district.

In the northern Himalayan state of Himachal Pradesh, five more people were killed since late on Monday as the death toll caused by landslides and flash floods rose to 31.

Officials in neighbouring Bangladesh, which has also been hit by bad weather and rising rivers, said 38 new deaths were reported overnight, taking the toll in the flooding to 443.

"The number of diarrhoea patients in some flood-affected areas have almost doubled in 24 hours," a doctor said.

So far, more than 50,000 people have been treated for diarrhoea and dysentery in the flooded districts, of which 18 have died, health officials said. (For more information about South Asia floods, visit Reuters AlertNet http://www.alertnet.org email: alertnet@reuters.com; +44 207 542 5791) (Reporting by Bappa Majumdar in Kolkata, Geetinder Garewal in Chandigarh and Serajul Islam Quadir in Dhaka)

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