Former BJP leader Babul Supriyo formally resigned as an MP on Tuesday, a month after he quit the party to join the Mamata Banerjee-led TMC.

Supriyo thanked the BJP leadership for the confidence they had shown in him.

"My heart is heavy as I had began my political career with the BJP. I thank the PM, party chief, and Amit Shah. They showed confidence in me. I had left politics wholeheartedly. I thought that if I am not a part of the party, I should not keep any seat for myself," he said after meeting Lok Sabha Speaker Om Birla.

The development comes after the two-term MP from West Bengal's Asansol had on September 20 -- two days after joining the state's ruling Trinamool Congress party -- written to Birla, seeking a "brief" appointment with him to formally resign as a member of the House.

The singer-turned-politician has repeatedly stressed that he did not want to continue as an MP since he was no longer a member of the party for which he won the seat.