Mamata Banerjee on Thursday said she might decide to go alone in the fight against the BJP’s new citizenship regimen and announced she would boycott the national Opposition meeting called by Sonia Gandhi on Monday, prompting the Congress and the Left in Bengal to cry foul.

The Trinamul Congress chief attributed her stand — which delighted the BJP, according to sources in its state unit — to the violence allegedly unleashed by the Congress and the Left in Bengal during the central trade unions’ 24-hour bandh on Wednesday.

“I have decided to boycott the January 13 meeting convened by Sonia Gandhi. I cannot condone the violence unleashed in Bengal yesterday. Such dirtiness,” the chief minister said in the Assembly.

She lost her cool when the Left targeted her for ruling out the need for a Kerala-like resolution in the Bengal Assembly against the Citizenship (Amendment) Act.

“You (the Left and the Congress) follow one policy in Bengal and a totally contradictory policy in Delhi. I do not want to be in this with you. If necessary, I will fight alone,” Mamata said, prompting the Left and the Congress to accuse her of being in a secret entente with the Narendra Modi government.

Left legislature party leader Sujan Chakraborty and leader of the Opposition Abdul Mannan of the Congress held a joint news conference later, accusing Mamata of backing out of the meeting by giving “flimsy excuses” after being reprimanded by “her Delhi bosses”.

“What dirtiness is she talking about? The bandh was an all-India phenomenon. Just because she doesn’t like these things now, the protest cannot stop in its tracks at Bengal’s borders. It seems she was scolded by her Delhi bosses because the bandh was successful here as well. That is why she has decided to boycott the meeting,” Mannan said.

While sources in the BJP state unit expressed joy over the “cracks” in the anti-BJP space “getting wider”, its state president Dilip Ghosh said such meetings were “laughable”.

The Monday meeting, according to a Trinamul sources, is to be a show of Opposition unity against the Modi government to take stock and decide on the course of action while the BJP seeks ways to counter the unprecedented resistance from across the country in the wake of the passing of the amended citizenship law and attacks on campuses.

Mamata pointed out that she had been leading the protests from the front — she led yet another mass march, from Madhyamgram to Barasat, shortly after — and it was her idea to have such a meeting.

Sources said she had wanted a senior non-Congress leader, such as NCP chief Sharad Pawar, to convene the meeting.

“I hereby seek the forgiveness of those who will attend the meeting,” Mamata said, adding that she had called up Pawar and informed him of her decision.

After the march in North 24-Parganas, attended by tens of thousands, Mamata told the gathering that Trinamul’s students’ wing would launch an indefinite sit-in on Rani Rashmoni Avenue till the Centre commits to withdrawing its citizenship regimen.

“As long as I am alive, there will be no CAA, NRC, NPR in Bengal…,” she added.