Somen Mitra blasted at Mamata Banerjee for "weakening" the opposition unity. (FILE PHOTO)

West Bengal Congress president Somen Mitra on Saturday blamed Chief Minister Mamata Banerjee for the rise of the Bharatiya Janata Party and the Rashtriya Swayamsevak Sangh in the state, saying had she not pursued the policy of "blatant minority appeasement", the BJP would not have gained footing in Bengal.

The Bengal Congress chief alleged that Ms Banerjee - who had been poaching leaders of the opposition parties - was now facing difficulty to protect its own existence, hinting at the exodus of Trinamool Congress leaders to the BJP.

Talking to reporters in Kolkata, Mr Mitra blasted at Ms Banerjee for "weakening" the opposition unity which helped the BJP in the recently-concluded general election.

In the non-BJP camp, the TMC, Communist Party of India (Marxist) and Congress fought separately in West Bengal.

The BJP bagged 18 Lok Sabha seats in Bengal out of a total of 42, only four less than the TMC. Congress managed to win two seats, down from four in 2014. The CPI-M, which ruled West Bengal for 34 years, drew a blank.

Buoyed by the massive victory, BJP leaders have been asserting that they will overthrow the Trinamool Congress government in the 2021 assembly polls.

"Mamata Banerjee is solely responsible for the rise of BJP and RSS in Bengal. Had she not pursued the policy of blatant minority appeasement, BJP wouldn't have found a footing in Bengal.

"Her policy of removing all opposition, poaching on opposition leaders and representatives has only led to the rise of BJP. Now she has no right to complain about it," Mr Mitra told reporters.

Those who once strengthened the hands of the BJP to weaken the Congress will now find it difficult to protect their own existence, Mr Mitra said apparently referring to flight of TMC leaders to BJP in Bengal.

"Even before elections, Mamata Banerjee was busy with her dreams of becoming Prime Minister. Time and again she had tried to undermine the Congress leadership," Mr Mitra, who replaced Adhir Ranjan Chowdhury as West Bengal Congress president in September last, said.

Mr Mitra also said that had there been a CPI (M)-Congress alliance in the state, the march of the BJP could have been stopped in West Bengal.

"The CPI(M) was not serious about alliance. They tried to impose their decisions on us. That''s the reason the alliance didn't work out," he said.