Manoranjan Byapari is a first-time MLA who won from Hooghly in last year's Bengal election.
A Trinamool Congress MLA's year-old anti-Bihar rant has become a huge embarrassment for Mamata Banerjee's party in Bengal. Trinamool MLA Manoranjan Byapari calls people from Bihar a "bimaari" or disease and says Bengal should be "disease-free", in a video that has been shared by BJP leaders.
"If Bengali blood runs through your veins...If the blood of Khudiram and Netaji (Subhash Chandra Bose) runs through your veins and if you love your mother tongue and motherland, then you have to shout out loud - 'Ek Bihari, sou bimari' (One person from Bihar is equal to 100 diseases)'. We don't want diseases. Make Bengal disease-free. Jai Bangla, Jai Didi Mamata Banerjee," Manoranjan Byapari said at the Kolkata Book Fair. The video is believed to have been filmed last year.
He was also heard saying: "If everything is fine in Bihar, then s***la go back to Bihar."
The Trinamool has distanced itself from the comments but the MLA said he never meant to target an entire community. "I only talked about some people in the community," said Mr Byapari.
The BJP's Suvendu Adhikari, a former Trinamool Congress leader, shared the video on Twitter and targeted Chief Minister Mamata Banerjee.
"First his leader Mamata Banerjee labels Biharis and UPites (those from Uttar Pradesh) as 'Bohiragotos' (outsiders) and now this clarion call to make Bengal free of Biharis," Mr Adhikari wrote.
He also needled Shatrughan Sinha, the actor-politician from Bihar who was recently named as a Trinamool candidate for bypolls in Bengal.
"My humble question to Bihari Babu Shri Shatrugan Sinha. Sir, what do you feel about this disgraceful rant of TMC MLA Manoranjan Byapari? Your new party colleague is very transparent about his feelings towards Biharis," Mr Adhikari tweeted:
"Adhikari is a rival, he is targeting me. He is picking on me to show me down," Mr Byapari said.
"I would never say anything about Shatrughan Sinha. I only meant those who insult Bengalis and our culture."
Shatrughan Sinha is contesting the bypolls from Asansol, which fell vacant after Babul Supriyo quit the BJP and joined the Trinamool Congress last year. Mr Supriyo is also contesting the bypolls but from Ballygunge.
Mr Byapari is a first-time MLA and former rickshaw-puller who won from Hooghly in last year's Bengal election. According to reports, he learnt to read in prison when he was 24 and went on to write several books.