By Waliur Rahman
BBC correspondent in Dhaka
India's controversial plans to divert water from international rivers in the east to arid areas in the south-west have come under fire.
India plans to tackle the cycle of flood and drought
Bangladesh handed a protest note expressing concern at the $100bn project to India's acting ambassador on Wednesday.
The government in Dhaka fears that India's plans could lead to ecological disaster.
India's ruling party, the BJP, wants to link 30 major rivers and divert their flow to water-deficient areas in the south-west.
Floods and drought have become a recurring problem in India and the project is aimed at improving the situation.
But the plans have caused much anger in Bangladesh.
The country, a delta at the mouth of several large rivers draining into the Bay of Bengal, depends on the flow of 54 rivers that enter its territory from India.
Dhaka fears that diversion of water from the Brahmaputra and the Ganges, which provide 85% of the country's fresh water flow in the dry season, would cause an ecological disaster.
Reports say the Indian National Water Development Agency plans to dig hundreds of reservoirs and more than 600 canals.
These will link 30 north-eastern rivers with rivers draining into south-western India.
Up to a third of the flow of the Brahmaputra and other rivers could be diverted to provide 173 billion cubic metres of water a year, the reports say.
"We have requested them not go ahead with the reported plan," Bangladesh Foreign Secretary SM Chowdhury said.
"We think it won't be a wise thing to do because it would affect Bangladesh ecologically and economically."