Roy, who won this year’s assembly election from Krishnanagar Uttar’s seat on a BJP ballot, joined the ruling Trinamool Congress last week. Previously at TMC, he had joined the BJP in 2017 and was its national vice president.
Spokesman Banerjee did not comment on the letter as he was not in the assembly.
Adhikari had recently met with Governor Jagdeep Dhankhar and complained about Roy.
BJP MP Rajya Sabha Swapan Dasgupta said the “law requires” Roy to resign as MLA as he was elected under the BJP symbol. “There was no ambiguity about his defection … Let him go his own way to resign from Rajya Sabha in 2017 before joining the BJP,” he tweeted. Meanwhile, TMC Secretary General of State Kunal Ghosh said the opposition leader should ask his father, Sisir Adhikari who joined the BJP in March, to “resign as a deputy of our party before asking others “.