West Bengal Chief Minister Mamata Banerjee said on Saturday that she has been informed that the Central government has filed caveats in Central Administrative Tribunal (CAT) and Calcutta High Court with regard to the transfer of West Bengal Chief Secretary Alapan Bandyopadhyay to Department of Personnel and Training in New Delhi..The State government may also be forced to explore legal options in view of Bandyopadhyay's transfer, Banerjee said. .The Chief Minister was addressing the media on the issue and sought to highlight how the transfer was "unconstitutional and illegal."."Move to transfer Chief Secretary Alapan Bandyopadhyay to Centre is unconstitutional and illegal. it is like bulldozing the basic structure of the Constitution. There needs to be some constitutional courtesy. State and Centre need to work together," said the Chief Minister. .Banerjee stated that though the State has not moved any legal forum, she has been informed that Centre has filed a caveat in CAT and High Court. ."We have come to know that they (Centre) have filed a caveat in the high court and CAT. We did not go to court. But if they want to go to court, we may have to. It cannot be a one sided litigation," said the Chief Minister. .She stated how "efficient" the Chief Secretary was and that Bandyopadhyay's image was being "tarnished" at the fag end of his career. .Centre on May 28 issued an order to recall West Bengal's top bureaucrat from the State on a day a row broke out over a meeting between Prime Minister Narendra Modi and Chief Minister Mamata Banerjee. Bengal Chief Secretary Alapan Bandyopadhyay's tenure was extended for three months only four days ago, before Friday's order to recall him was passed..The development came hours after Banerjee skipped a meeting with PM Modi to assess the impact of Cyclone Yaas, choosing instead a quick 15-minute interaction with him at an airbase where his flight landed. She was to attend a cyclone damage review with PM Modi but left after handing him a report. The centre alleged Ms Banerjee kept PM Modi and governor Jagdeep Dhankhar waiting for half an hour.