The Calcutta High Court on Thursday rejected the bail plea of West Bengal transport minister Madan Mitra, arrested by the CBI in the multi-crore Saradha scam.Former union minister and senior advocate Kapil Sibal argued for Mitra before a division bench of Justices Nishita Mhatre and Asha Arora.The CBI counsel opposed the bail plea, contending that Mitra was an influential person and his release on bail would hamper investigation.After hearing both the parties, the court rejected Mitra's bail plea.Charge-sheeted for various offences, including criminal conspiracy, cheating and criminal breach of trust in the multi-crore scam, Mitra has been behind bars since his arrest by the Central Bureau of Investigation on December 12 last year.