Former Calcutta mayor Sovan Chatterjee, once seen as a close ssociate of Mamata Banerjee, joined the BJP on Wednesday.

Chatterjee, also a former minister of the Mamata government, joined the party in the presence of its senior Bengal leader Mukul Roy and general secretary Arun Singh.

Welcoming Chatterjee, Roy said he was one of those leaders who has made a big contribution to Banerjee's rise to the post of chief minister.

'He will now strengthen the BJP.... Let me repeat that TMC will not even get the status of the Opposition party,' he told reporters.

Six Trinamul MLAs, and one each of Congress and CPM have switched over to BJP since the results of the Lok Sabha polls were announced in May, with the saffron party wooing rival leaders to bolster its strength in the run-up to the next Assembly polls in the state, due in 2021.

The BJP made deep inroads in Bengal in the Lok Sabha polls by winning 18 out of the 42 Lok Sabha seats.