Mamata Banerjee on Saturday demanded a joint river commission with Bhutan, adding a new challenge for India’s hydro diplomacy at a time New Delhi is courting Bangladesh with an offer to renew the Ganga Water Sharing Treaty and a conservation and management plan for the Teesta.

The Bengal chief minister, who attended a Niti Aayog meeting in Delhi, underscored the need for such a joint commission while highlighting the flooding caused in north Bengal by rivers flowing in from the Himalayan country.

“Many rivers flow into the Alipurduar and Jalpaiguri districts from Bhutan. Because of flash floods in these rivers, vast areas of these districts get inundated every year,” she said at Calcutta airport after returning from Delhi.

“Also, the rivers erode chunks of land. To address this problem, I suggested at the Niti Ayog meeting that a joint river commission be formed with Bhutan.”

Mamata added: “I had submitted a written speech there.... However, this issue was not mentioned there and, therefore, I mentioned it separately.”

Sources in the state irrigation department said around 45 streams and rivers flow into India from Bhutan, which borders the Darjeeling, Jalpaiguri and Alipurduar districts as well as Assam.

Some of the prominent rivers flowing into the north Bengal districts include the Raidak, Torsha, Sankosh, Pana and Basra (Alipurduar) and the Diana and Reti-Sukriti (Jalpaiguri).

“Many hilly streams flow into rivers downstream. During the monsoon months, when it rains in the upper catchment areas (in Bhutan), the rivers swell and cause flash floods,” an official said.

On Friday, the Bengal Assembly had passed a resolution demanding a joint river commission with Bhutan.

Four Trinamool Congress MLAs, who are also state ministers, had moved the resolution along with Suman Kanjilal, the Alipurduar MLA who has defected from the BJP to Bengal’s ruling party.

The resolution said the state would ask the Centre to initiate talks with Bhutan for the formation of a joint river commission. On July 29, when Mamata is expected to attend the Assembly, a discussion will be held on the matter.

A former state irrigation department official said that since many rivers from India flow into Bangladesh, a joint river commission between the two countries was formed in 1972 to share water-flow data and discuss river-related issues.

“A similar commission with Bhutan will help address the problems of flash floods and erosion in parts of north Bengal. Most of the rivers that flow into India from Bhutan merge with the Brahmaputra, which eventually flows into Bangladesh from Assam. It will be interesting to see what the Centre does,” he said.

Mamata’s demand for a joint river commission with Bhutan comes at a time when India’s hydro diplomacy with Bangladesh is facing several challenges.

During Prime Minister Sheikh Hasina’s India visit last month, New Delhi had announced plans to renew the Ganga Water Sharing Treaty — signed in 1996 and due to expire next year — and send technical teams to Bangladesh to draw up a project for the conservation and management of the Teesta.

India is keen to address Bangladesh’s concerns about water sharing, particularly since China has already come up with a proposal to help Dhaka with the management of the Teesta.

Although Hasina, who recently visited China, said on her return from Beijing that she would be happy if India took up the project, the last word on the Teesta is yet tobe heard.

Mamata, who has always described Bangladesh as a “friendly neighbour”, reiterated on Saturday that the Modi government had floated the proposals on the Ganga and the Teesta while keeping Bengal in the dark.

“It is up to you what you will give another country... but when the state (Bengal) is a stakeholder, how can you decide without consulting the state?” she said.

“In both these cases, India, Bangladesh and Bengal should together participate in the talks. They (the Centre) didn’t seek any opinionfrom us.”

Her remarks were in line with the Assembly resolution, which says the Bengal government will ask the Centre to consult the state onboth issues.

Mamata said the Teesta lacks adequate water during the non-monsoon months. “If water is provided (to Bangladesh), the people of north Bengal will not get drinking water. They (the Centre) should keep that in mind.”

She castigated the Centre for failing to provide funds for anti-erosion and flood protection measures in Malda and Murshidabad, which are on the left and right banks ofthe Ganga.

“When the (Ganga) treaty was signed, a project of ₹700 crore was planned to curb erosion in these districts,” Mamata said.

“No funds have been allocated so far, and the lack of dredging of the Ganga riverbed in Farakka causes areas downstream to get flooded. I want to know whether mentioning these issues (at the Niti Aayog) was a crime.”

Mamata, who had walked out of the Niti Aayog meeting midway, has alleged her mike was switched off.