They were admitted to the state-run SSKM hospital where they have been kept on oxygen support.
This comes a day after they were arrested by the CBI along with two state ministers – Firhad Hakim and Subrata Mukherjee.
“Chatterjee and Mitra complained of breathlessness at around 3 am, following which they were brought to the hospital. Both have been kept on oxygen support at the Woodburn Ward of the SSKM Hospital. They are stable now,” an official was quoted as saying by PTI.
All four leaders were taken to Presidency Correctional Home in Kolkata late on Monday night.
Mukherjee, who fell sick in the correctional home, was also taken to the hospital for a check-up early on Tuesday.
He was taken back to jail after the check-up. The official said the minister did not want to get admitted to the hospital.
On Monday, a special CBI court granted bail to all four leaders, however, the bail was stayed by the Calcutta High Court after the CBI challenged the order.
A division bench said that they shall be treated to be in “judicial custody till further orders”.
Chief Minister Mamata Banerjee, other TMC leaders and supporters had staged a protest at the CBI office in Kolkata following the arrest of the four.
TMC party supporters raised slogans against the BJP- led NDA government, and hurled stones and bricks at security personnel outside Nizam Palace, which houses the CBI office here, protesting the arrests.
The TMC has accused the BJP of witch-hunt saying that they are protecting their own party leaders allegedly involved in the case such as Suvendu Adhikari and Mukul Roy.