Guwahati, May 14: Assam chief minister Tarun Gogoi has urged Prime Minister Narendra Modi to take up the issue of big dams coming up on the Brahmaputra with Beijing during his three-day visit to China, which began today.

Gogoi said there have been serious concerns about the construction of dams by China over the Brahmaputra (known as the Yarlung Tsangpo in the neighbouring country) as it would have an adverse downstream impact in India, particularly in Assam.

Modi has reached China and will be holding talks with Chinese president Xi Jinping and premier Li Keqiang on wide-ranging bilateral issues.

The Tsangpo enters India through Arunachal Pradesh before flowing through Assam and then into Bangladesh.

In November, China had commissioned its first major dam (510MW Zangmu dam), the construction of which began in 2010, on the middle reaches of the Brahmaputra in Tibet.

It is also said to be working on three more projects at Dagu, Jiacha and Jiexu.

After the commissioning of the Zangmu dam, China had reassured Indian officials that it would have no downstream impact, as it was a run-of-the-river project. It also said there will be no diversion of the Brahmaputra, another cause of worry downstream.

"Prime Minister Narendra Modi must convey India's concerns to Beijing during his visit," Gogoi said in an official communiqué released here this afternoon.

In 2011, then Prime Minister Manmohan Singh, a Rajya Sabha member from Assam, had said in Parliament that the Zangmu dam was a run-of-the-river project following concerns in the state over the impact of the dams being built/proposed in the neighbouring country.

During Singh's tenure, both countries had signed a pact in 2013 allowing Indian hydrological experts to conduct study tours to monitor the river's flows in Tibet, sources said.

"Since Assam strongly feels damming the Brahmaputra will leave the downstream areas parched, it has been raising the issue at regular intervals. Prime Minister Modi's visit has come as another opportunity to broach the topic," a source in the chief minister's office said.