The Assembly unanimously passed a resolution that vowed against the “partition of West Bengal” on Monday after the Trinamul Congress accepted a key amendment proposed by the BJP.

That Treasury benches incorporated the Opposition’s suggestion in a motion was a first since Mamata Banerjee became the Bengal chief minister in 2011.

In the morning, parliamentary affairs minister Sobhandeb Chattopadhyay, along with his three cabinet colleagues, Aroop Biswas, Shashi Panja and Biplab Mitra, moved the motion under Rule 185 of the Procedure and Conduct of Business.

The resolution that spoke against the alleged attempts to divide Bengal was opposed by BJP MLAs as it mentioned that a junior Union minister wanted to include north Bengal in the North Eastern Council. The motion was referring to the demand from Sukanta Majumdar, who is also the Bengal chief of the BJP.

Leader of the Opposition Suvendu Adhikari said the demand had been made to secure a portion of the funds allocated for the Northeast.

“The Centre has allocated 10 per cent of the budget for the development of the Northeastern states and if north Bengal is included in the North Eastern Council, then it would allow north Bengal districts to get a portion of the funds which can be used for the development,” he said.

Adhikari proposed that if the ruling party kept the resolution simple and mentioned only the opposition to dividing Bengal, the BJP would fully support it.

“We are against any kind of division of the state,”he said.

In response to the proposal, Mamata said: “I will ask the Speaker to add the line suggested by the leader of the Opposition in the resolution.... I am always in favour of constructive, positive criticism and genuine feedback.”

Speaker Biman Banerjee allowed the new motion.

“We will protect the integrity of the state at any cost. We will not allow the partition of West Bengal,” read the motion that was passed unanimously.

A senior member of the Treasury benches said Mamata’s move was a “diplomatic masterstroke”.

“By accepting Suvendu’s proposal, she showed her willingness to cooperate when the criticism is constructive, and that she is open to amicable resolutions when approached properly. Then, by changing the language, she prevented any division in the House,”he said.

“Finally, she had the BJP lawmakers state on the record in the House that they, too, are against any division of the state,” he added.

The TMC moved the resolution in the wake of several recent statements by BJP leaders for the division of Bengal.

While addressing the House after Adhikari, Mamata said: “I have always believed in cooperative federalism where all political parties will work for the development of the country. That is why I went to the meeting of Niti Aayog.”

Responding to Adhikari’s reference to the chief minister’s visit to BJP Rajya Sabha member Nagendra Ray, Mamata asked: “What is the problem if I did?”

“He had called me over for tea. You (Adhikari) call me to your home and I will come... no problem,” she said to applause and laughter in the House.

Speaking to journalists outside the Assembly, Adhikari said the previous motion was politically motivated and read like a “pamphlet”.

“We opposed and they finally agreed.... I think they are taking lessons from the Parliament on how to behave with the Opposition,” he said.