A controversial dam project by India on a common river with Bangladesh is threatening to cloud a visit by Bangladeshi Prime Minister Sheikh Hasina to New Delhi starting on Sunday. Following are some questions and answers about the controversy over the Tipaimukh dam that India expects will help tackle floods and also produce hydel electricity. Hasina will discuss the issue with her Indian counterpart, Manmohan Singh. What is the Tipaimukh Dam project? India has approved plans for a 1,500-megawatt hydroelectric dam in northeastern Manipur state on the Barak River, which flows into Bangladesh before emptying into the Bay of Bengal. Why is it controversial? The Tipaimukh dam may affect the life and livelihood of some 20 million Bangladeshis living in the northeastern region, with farming, fishing, carrying merchandise on boats their main occupation. About 100 villages in India's Manipur could also be inundated. Some experts have warned that two rivers in Bangladesh's Sylhet region – the Surma and Kushiara – will dry up if India dams a third river, the Barak, at Tipaimukh. Dhaka says it will carefully inspect and evaluate the plan before confirming India can go ahead with the dam. Who could gain? Originally designed to contain floods in the region, the dam was turned into a power project by India, where electricity shortage – pegged at 16.6 percent during hours of peak consumption last year – is a daunting barrier to development. The proposed dam offers the possibility of India selling some of the power it generates to Bangladesh. Hasina's government says it is trying to address nagging power shortages that have slowed industries and kept investors away. Hasina is also likely to discuss buying electricity while in New Delhi. Why is it a political issue in Bangladesh? The main opposition Bangladesh Nationalist Party (BNP) of former prime minister Begum Khaleda Zia has threatened to launch a massive street protest if Hasina agrees to the building of the dam by India. Government officials say BNP is trying to make noise over the Tipaimukh dam for political gains by provoking anti-India sentiment. Hasina's rivals are also opposing plans by her to sign a deal with New Delhi on sharing of water from the Teesta, which is among several rivers flowing from the Himalayas into Bangladesh, providing a lifeline to both farming and ecology in both countries. They say the deal favors India. India and Bangladesh already have a water-sharing pact for the Ganges.