New Delhi/Kolkata: Top Trinamool Congress leader Mukul Roy has been asked by CBI to appear before it in the Saradha chit fund scam probe, drawing angry reaction from the party which accused BJP of using the agency as a "political tool".

"I have been asked by the CBI to appear (before it). I am in Delhi for a day or two and as and when I will return to Kolkata, on the first occasion, I will meet the CBI people," Roy, TMC Rajya Sabha MP and a close confidant of Chief Minister Mamata Banerjee, said on Monday.

"I have never been involved in any way in any immoral and illegal activity as an individual or as custodian of my party," the former Union minister, who is TMC's all India general secretary, asserted.

In a statement, Derek O'Brien, national spokesperson and Chief Whip in the Rajya Sabha, said, "The nasty ploy of using CBI as a political tool by BJP continues. They could not fight us politically in Bengal in the Lok Sabha elections, so now these dirty tactics months before corporation elections. We will fight them ‘strongly, politically".