Bangladesh Nationalist Party (BNP) chairperson, Khaleda Zia, transferred to hospital last weekend from the 19th-century jail where she is the only prisoner, can no longer use her left hand, her physician told AFP on Tuesday.
Khaleda Zia, 73, was jailed in February for corruption and has been on trial in a special room in the abandoned Dhaka Central Jail on additional graft charges that her supporters say are politically motivated.
On Saturday Zia, a long rival to prime minister Sheikh Hasina, was transferred to hospital because of poor health following an order from the High Court.
"Her symptoms have worsened in the last few months," Abdul Jalil Chowdhury, one of the physicians at the Bangabandhu Sheikh Mujib Medical University (BSMMU) hospital who has since examined her, told AFP.
"She has developed deformity of left hand in the last few months due to long standing rheumatoid arthritis. She cant use her left hand," he said.
"In addition, she has developed left frozen shoulder," he said, adding Khaleda Zia was also suffering from neck and back pain and she is a diabetic.
Lawyers for Zia, prime minister from 1991-1996 and 2001-2006, had argued that the government was putting her health at risk by refusing her specialised care in prison.
When Khaleda Zia -- who leads the Bangladesh Nationalist Party -- was jailed in February for corruption, the sentence triggered clashes between police and thousands of BNP supporters.
She was found guilty of embezzling money intended for an orphanage.
Khaleda Zia is appealing against the verdict -- which bars her from standing in the general election set for December -- and was granted bail earlier this year.
However she remains in custody while she fights dozens of other violence and graft charges.
Last month the authorities turned a room of the jail into a court -- a move her lawyers said was illegal.
Khaleda Zia already had health issues including arthritis, diabetes and knee replacements when she was sentenced.
She is the only inmate in Dhaka Central Jail, built in the 19th century under British colonial rule and declared abandoned in 2016.
Her party boycotted the 2014 election in which Sheikh Hasina returned to power but is expected to contest the election due in December.