Kolkata, April 2 (IANS): West Bengal's ruling Trinamool Congress on Thursday said the CBI called up its state headquarters during the day, looking for its national general secretary Subrata Bakshi, and lashed out against the central agency "which has lost its credibility".

In an apparent reference to the Bharatiya Janata Party, that leads the National Democratic Alliance government at the Centre, Trinamool secretary general Partha Chatterjee accused the Central Bureau of Investigation of working "at the behest of a political party".

"CBI has lost all its credibility. It is acting at the behest of a political party," he said.

He claimed that the CBI swung into action after the Trinamool announced a protest programme against the land ordinance earlier in the day.

Chatterjee also charged the central probe agency of "acting with a political motive" ahead of the civic elections slated to be held in the state later this month.

He said the CBI officer, who made the telephone call, asked for Bakshi's number.

"The CBI wanted Bakshi's number. It was given as we have nothing to hide. Trinamool is a transparent party," he said adding that if CBI sent a letter, then the Trinamool would give it a reply.

"Everyday, we receive hundreds of letters. We reply to them. If we receive any letter from CBI, we will reply to it too," he said.

"Before the by-polls at Bongaon and Krishnaganj, CBI had tried to do the same thing. We are also questioning the timing of the phone call to the all India general secretary of the party just before the municipal polls," he said.

The CBI, which is probing the multi-billion-rupee Saradha chit fund scam, had summoned party general secretary Mukul Roy - now estranged from the party leadership - for questioning in January. The by-polls to the Bongaon Lok Sabha constituency and Krishnaganj assembly seat were held in February. Trinamool won both the seats.