Hours after Trinamool Congress (TMC) leader and Chief Minister Mamata Banerjee's man Friday Mukul Roy announced his resignation in a sudden press conference, party came out with a rebuttal and said that Mukul Roy has been expelled from the party for six years.

Hours after Trinamool Congress (TMC) leader and Chief Minister Mamata Banerjee's man Friday Mukul Roy announced his resignation at a hastily called press conference, party came out with a rebuttal and said that Roy had been expelled from the party for six years.

"We are concerned about our own party. Roy has been unfaithful to the party and our leader. Mamata Banerjee gave him everything — he became railway minister, he was the member of Rajya Sabha — what else do you want? Mamata put a lot of a trust in Roy and he betrayed the party and our leader," Party secretary general Partha Chatterjee said at a press conference in Kolkata.

Chatterjee added that Roy was colluding with TMC's arch rival BJP and was acting against the Trinamool's interest. "The party has suspended Roy for six years for anti-party activities and colluding with the BJP," said Chatterjee.

Earlier in the day, Roy, once a senior and an influential leader in the TMC ranks, said he would resign as the primary party member and also from his Rajya Sabha seat after the Durga Puja which concludes on 30 September.

"With a heavy heart and pain, I am informing you that I have taken a principled decision. I am not an office-bearer in the party now... I will mail my resignation from the party working committee today itself. I'll quit as Rajya Sabha member after the Durga Puja break. I will also quit my primary membership of the Trinamool after a few days," Roy added.

Refusing to divulge more, Roy said he would explain the reasons for his decision later. "Today is panchami. People of Bengal and in the rest of India are in a festive mood. People will not accept it if I say these things now," the former railway minister said.

Roy, one of the founding members of the TMC, also recalled that he was the first signatory for the party on 17 December, 1997, during the its formation process. TMC officially came into being on 1 Janauary, 1998.

Completely sidelined in the party for months, speculation about Roy quitting the TMC was rife for weeks, as he gradually distanced himself from it, and was said to be scouting for a new political innings with some other party, particularly the BJP.

Once regarded as the Man Friday of Banerjee, Roy had wielded enormous clout in the party's all powerful national general secretary for decades since its formation, and was widely regarded the main architect of its electoral successes.

Known for his composure, shrewdness and organisational ability, Roy even purportedly called the shots with regard to promotions and postings of key administrative and police officers after the party came to power in the state in 2011

Roy's formal announcement of snapping ties with the TMC came three days after party general-secretary Partha Chattejree issued him a strict warning for "hobnobbing with the BJP" and said "we are keeping a close watch on him".

A series of events seem to have prompted Roy's decision to leave the TMC, a somewhat ironic development in the sense that he had been chiefly instrumental in engineering defections from various parties to the TMC for years, with the Opposition time and again crying foul about his "strategies of coerciveness and inducements".

Last week, Roy sent back the state police personnel providing him Z category security cover after Banerjee, in an organisational reshuffle, abolished the vice-president's post he had been holding for over a year.

He was also kept away from several party programmes and sacked as the party in-charge of Tripura.

This was the second time that Roy had been estranged from the TMC.

He first fell out with the party following his grilling by the Central Bureau of Investigation (CBI) in January 2015 in connection with the Saradha ponzi scam.

As Roy started skipping TMC meetings, Banerjee stripped him of all his posts, and relegated him to the Rajya Sabha's back benches.