Kolkata, Dec 12 (IANS): The Trinamool Congress Friday termed the arrest of West Bengal Transport Minister Madan Mitra as "politically motivated", and claimed the decision to arrest him was taken when BJP president Amit Shah had come to Kolkata and met the CBI.

"The CBI called Madan Mitra for testifying/questioning and without any information to anybody arrested him. The CBI is being directed not just by the BJP, but by BJP leader Amit Shah himself," said Trinamool leader Subrata Mukherjee.

"When Amit Shah had come to Kolkata, a decision was taken to arrest Mitra during a meeting with the CBI and him at that time," he said.

The Trinamool hit out at the BJP for resorting to politics of "vindictiveness".

The Central Bureau of Investigation (CBI) Friday arrested Trinamool leader Mitra in connection with the multi-crore-rupee Saradha chit fund scam.

"Even before Amit Shah came to Kolkata, it was decided that the CBI would arrest Mitra. This arrest is politically motivated. The BJP is doing politics of vindictiveness," said Mukherjee.

Mitra was arrested on prima facie evidence of criminal conspiracy, cheating and misappropriation as well as deriving undue financial benefits from the Saradha group, according to a CBI spokesperson.

Mukherjee said Trinamool was mulling introduction of a privilege motion to counter the politics of the Bharatiya Janata Party.

"We are exploring all options. We may bring a privilege motion.

"How can the government and assembly speaker be kept in the dark before arresting a cabinet minister?" Mukherjee questioned, adding it was "undemocratic".

Education Minister Partha Chatterjee later announced a rally Saturday with sportspersons to protest the arrest.