RJD president Laloo Prasad Yadav, lodged in Beur jail has been taken ill and advised complete bed rest.
Patna civil surgeon Dr A K Mishra, who examined Yadav along with some other senior doctors on Monday evening within the jail premises, said he had complained of cold and cough.
On being examined he was found to have fever and his blood pressure had also shot up, Mishra said on Tuesday.
A team of specialists led by head of department of medicine, Patna medical college hospital, Dr Gauri Prasad Singh examined the RJD chief again Tuesday morning.
However, Yadav would not like to be shifted to hospital and would prefer to stay in the jail, sources close to him said.
Yadav was brought here from Ranchi by a state plane on Monday in connection with the disproportionate assets case, an offshoot of the fodder scam on December 6.
He was remanded to judicial custody on November 26 by CBI judge H C Mishra in Ranchi in connection with a conspiracy angle case of the fodder scam.