Mamata Banerjee addresses a Trinamool Congress rally in Kolkata

Under pressure after the arrest of her key aide Madan Mitra in the Saradha scam, Trinamool Congress chief Mamata Banerjee today hit out directly at Prime Minister Narendra Modi. Arguing that an image of Madan Mitra with the man who ran Saradha should not be considered proof of criminal conspiracy, Ms Banerjee asked, should the PM be arrested just because he has appeared in photographs with Sahara chief Subrata Roy?"If an image is a proof of criminal conspiracy, then PM should be arrested for Sahara Scam," Ms Banerjee said at a party rally in Kolkata."A red diary was obtained after raiding Sahara office. It had several big names. Empty vessels sound much," she added.The Sahara chief has been in Delhi's Tihar Jail since March after he failed to convince judges that he is serious about repaying nearly 20,000 crores for two Sahara bond schemes that were declared illegal in 2012.Ms Banerjee made these comments in a speech before leading a huge march of Trinamool supporters to protest Madan Mitra's arrest. The march was from the Goshto Pal statue near Eden Gardens to the Mahatma Gandhi statue on Red Road.Yesterday, after Mr Mitra's arrest, Ms Banerjee dared the PM and the BJP leadership to arrest her, alleging vendetta politics by the Centre. ( Read: "PM Modi, Arrest Me," Mamata After Minister Caught in Saradha Scam ) Today, she also slammed the Central Bureau of Investigation or CBI, which is investigating the Saradha scam, for Mr Mitra's arrest."CBI has lost all credentials. They have become His Master's Voice," Ms Banerjee said.Mr Mitra is the first minister of the ruling Trinamool Congress to be arrested in the scam in which lakhs of people were cheated out of their savings. Two party MPs, Srinjoy Bose and Kunal Ghosh, were arrested earlier.

Mitra was seen in video clips praising Saradha Group chairman Sudipta Sen at a meeting of Saradha agents and allegedly enjoyed benefits like a car, fuel and driver at the company's expense. He allegedly also extracted donations out of Sudipto Sen for a temple.The Trinamool will protest in Parliament on Monday against what it says is vendetta politics of the BJP.