New Delhi, Aug 14 (IANS): In a jolt to the Mamata Banerjee-led Trinamool Congress in West Bengal, former Kolkata Mayor Sovan Chatterjee joined the Bharatiya Janata Party (BJP) in New Delhi on Wednesday.

Chatterjee, considered a close aide to West Bengal Chief Minister Mamata Banerjee, has at least four decades of political experience with him. He is the sitting Trinamool MLA from Behala Purba Assembly constituency.

Along with Chatterjee, his friend and associate Baisakhi Banerjee also joined the BJP at the party's headquarters in the national capital. Banerjee has been described by the BJP functionaries as an educationist from West Bengal. She was the General Secretary of Trinamools' association for professors in West Bengal.

They joined the BJP in the presence of Arun Singh, the party's National General Secretary, and Mukul Roy, a former Trinamool Congress leader who had jumped ship to the BJP in 2017.

"Mamata's party will not even get Opposition party status in the forthcoming assembly polls in West Bengal. It is a big day for the BJP in Bengal. Sovan Chatterjee is a big name in Bengal politics," said Roy.

Party sources said that Chatterjee is the biggest catch of the BJP in West Bengal after Mukul Roy. His induction into BJP is expected to considerably dent Trinamool's stature in the state.