Roy, who won this year’s assembly election from the Krishnanagar Uttar seat on a BJP ticket, joined the ruling Trinamool Congress last week. Previously in the TMC, he had joined the BJP in 2017 and was its national vice-president.
Speaker Banerjee did not comment on the letter as he was not in the assembly.
Adhikari had recently met governor Jagdeep Dhankhar and complained about Roy.
BJP Rajya Sabha MP Swapan Dasgupta said the “law demands” that Roy resign as MLA as he was elected on the BJP symbol. “There was no ambiguity over his defection … Let him follow his own course of resigning from Rajya Sabha in 2017 before joining BJP,” he tweeted.Meanwhile, TMC state general secretary Kunal Ghosh said the leader of opposition should ask his father, Sisir Adhikari who joined the BJP in March, to “resign as our party MP before asking others”.