Kolkata, March 16 (IANS): In an apparent swipe at sidelined Trinamool Congress leader Mukul Roy, party secretary general Partha Chatterjee on Monday said anyone opposing his own party is akin to one who has "lost his mental balance".

"If someone is a member of the party and behaves like an opponent, then that person has lost his conscience and mental balance," Chatterjee told the media here.

He was quizzed on Roy's recent comments on being prevented from entering Nandigram and the subsequent reaction of the party.

In a guarded response, Chatterjee stressed on party discipline.

"Since he is a member of the party, the codes of discipline applies to him in the same manner it applies to the rest," he said.

Roy was prevented from entering Nandigram by his own partymen on March 14 - which the Trinamool observes as "Nandigram Divas" to pay homage to the 14 farmers, who were killed in police firing at the height of the anti-acquisition movement in East Midnapore district.

Stripped off of all party positions, the former party national general secretary sought to lead a separate march instead of participating in the Trinamool organised martyrs' rally. But his convoy was prevented from entering Nandigram by Trinamool activists, who waved black flags and flashed placards with "Mukul go back" on them.

Roy's three attempts to enter Nandigram proved futile even as his party peers including secretary general and state education minister Partha Chatterjee, urban development minister Firhad Hakim and MP Subhendhu Adhikari among others attended the rally.

Credited as the architect of Trinamool's electoral success and once considered to be Mamata Banerjee's closest confidante, Roy's relation with the party nosedived following his interrogation by the CBI in connection with the multi-crore rupee Saradha scam.

Going against the party stand that the CBI was targeting Trinamool leaders, Roy insisted he would cooperate with the probe agency even if it summoned him a hundred times.