Kolkata/IBNS/UNI: Former Bengal Congress leader Koustav Bagchi joined the Bharatiya Janata Party (BJP) on Thursday in the presence of party's state President Sukanta Majumdar and leader of the Opposition Suvendu Adhikari.

Bagchi joined BJP, a day after he quit the grand old party following its service to the same for 22 years.

Bagchi, in a letter to Congress national President Mallikarjun Kharge and its state chief Adhir Ranjan Chowdhury, had announced that he has resigned from all party posts.

"It is embarrassing and was hurting me, rather insulting me for some months now that many in the Congress opine that the TMC is the sister organisation of the Congress," Bagchi had told reporters.

Bagchi had also said he would start a new political innings and join a party that " really fights" against the Mamata Banerjee regime.

Bagchi went to the BJP office Thursday to pick up the saffron outfit's flag.

"We will fight together and work for Prime Minister Narendra Modi to win over 400 seats for the 2024 Lok Sabha poll and ensure his third straight term," he said.

"We will also work together to win 35 Lok Sabha seats in Bengal and fulfill the aspiration of Union Home Minister Amit Shah," the former Congressman added.