Mitra underwent a "regular medical check-up" and "There is nothing serious," SSKM hospital sources told PTI.
He was later taken back to Alipore Jail, a day after his bail plea was rejected.
Mitra, who is Transport and Sports minister, was arrested on December 12 and following two spells in CBI custody, he was sent to judicial remand on December 19.
He was, however, admitted to state-run SSKM Hospital on the same evening following complaints of chest pain and uneasiness.
A city court yesterday rejected Mitra's bail plea and remanded him in judicial custody till January 16. The Minister claimed innocence saying he was ready to be hanged if found guilty in the chit fund scam.
Mitra today hit out at the opposition for claiming that he was getting preferential treatment in jail.
"Those who are alleging that I am enjoying undue benefits inside the jail, I invite them to form an all-party committee of the West Bengal Legislative Assembly and visit me in the jail along with the CBI and see how I am actually staying there," he told reporters.
BJP's state chief Rahul Sinha yesterday alleged that Kolkata Police was giving preferential treatment to Mitra while taking him to the court from jail.
Incidentally, another accused in the Saradha scam, suspended Trinamool Congress MP Kunal Ghosh, had equated Mitra's stay at the SSKM with being in a hotel.
The magistrate had yesterday directed jail authorities to ensure medical aid to the minister.
