Zia, 80, who was admitted to hospital on November 23 with symptoms of a lung infection, was in a “very critical” condition, a member of her political party said late on Friday.
“Khaleda Zia is in intensive care and consultations with physicians are ongoing,” Ahmed Azam Khan of the Bangladesh Nationalist Party (BNP) told reporters outside the hospital in Dhaka on Saturday.
An air ambulance had been kept on standby to take Zia abroad for advance treatment if her condition stabilises, Khan said.
Several senior BNP leaders and anxious supporters visited the hospital to receive updates on her condition.
English-language newspaper, The Daily Star, said Zia has “heart problems, liver and kidney issues, diabetes, lung problems, arthritis, and eye-related illnesses”.
She has a permanent pacemaker and previously underwent stenting for her heart, the publication reported.
Zia’s eldest son, Tarique Rahman, who is based in London since 2008, called on the people of Bangladesh to pray for his mother’s recovery.
“We express our heartfelt thanks and gratitude for all your prayers and love for the highly respected Begum Khaleda Zia,” Rahman, 60, said on Saturday in a social media post.
“We fervently request you to continue your prayers for her early recovery.”
Rahman said he was unable to return to Bangladesh because of circumstances that were beyond his control.
“I share the same deep longing as any child to have my mother’s touch in moments of crisis. However, the decision to return home is neither straightforward nor mine alone to make,” he said.