in a project that has sparked concerns from India and Bangladesh. Chinese Premier Li Qiang presided over a ceremony marking the start of construction on the Yarlung Tsangpo river last Saturday, according to local media. The river flows through the Tibetan plateau. The project has attracted criticism for its potential impact on millions of Indians and Bangladeshis living downriver, as well as the surrounding environment and local Tibetans.

Beijing says the scheme, costing an estimated 1.2tn yuan ($167billion; £125billion), will prioritise ecological protection and boost local prosperity. When completed, the project - also known as the Motuo Hydropower Station - will overtake the Three Gorges dam as the world's largest, and could generate three times more energy. Experts and officials have flagged concerns that the new dam would empower China to control or divert the trans-border Yarlung Tsangpo, which flows south into India's Arunachal Pradesh and Assam states as well as Bangladesh, where it feeds into the Siang, Brahmaputra and Jamuna rivers.

A 2020 report published by the Lowy Institute, an Australian-based think tank, noted that "control over these rivers [in the Tibetan Plateau] effectively gives China a chokehold on India's economy". In an interview with news agency PTI earlier this month, Arunachal Pradesh chief minister Pema Khandu expressed concern that the Siang and Brahmaputra could "dry up considerably" once the dam was completed.

He added that the dam was "going to cause an existential threat to our tribes and our livelihoods. It is quite serious because China could even use this as a sort of 'water bomb'". "Suppose the dam is built and they suddenly release water, our entire Siang belt would be destroyed," he said. "In particular, the Adi tribe and similar groups... would see all their property, land, and especially human life, suffer devastating effects."

In January a spokesperson for India's ministry of external affairs said they had expressed concerns to China about the impact of mega-dams and had urged Beijing to "ensure the interests of downstream states" were not harmed. They had also emphasised the "need for transparency and consultation with downstream countries". (BBC/ Getty Images)