A lawyer for Thaksin Shinawatra is preparing all necessary documents to seek a royal pardon for the former prime minister.
Winyat Chartmontree, the lawyer, added that the date has yet to be scheduled. Normally, inmates who have served one-third of their sentence or been imprisoned for at least eight years can submit a request for a royal pardon.
Thaksin, 74, returned to Thailand after 15 years in self-exile and was sent to a quarantine area of the Bangkok Remand Prison on Aug 22 after the Supreme Court sentenced him to eight years in prison.
Within 13 hours, he was transferred to the Police General Hospital suffering from chest pain, hypertension, and low blood oxygen saturation.
Thaksin's youngest daughter Paetongtarn, visited her father on Monday afternoon and Tuesday morning. She said that she was most worried about his heart condition.
She told reporters at the Pheu Thai Party headquarters on Tuesday that her father was exhausted but could still talk to her.
"I am worried about his heart. He also has a lung illness, but that is an old issue and should not cause any acute problems. I am more worried about his heart," Ms Paetongtarn said.
Ms Paetongtarn said Thaksin had earlier caught Covid-19 before there was specific medication for it. He was kept in an intensive care unit for nine days and remained in hospital for a month.
There were still traces of the illness in his lungs, she said, but added that his morale remained strong.
Ms Paetongtarn confirmed that her father would remain at Police General Hospital and said there was no plan to move him to a private hospital.
Asked how long Thaksin would need to remain hospitalised, Ms Paetongtarn said she had asked doctors the same question but there was no answer yet because "there are many factors".
She denied he was in a VIP room at Police General Hospital. The view from the room was the Royal Thai Police Office, she said.
Asked about a possible request for a royal pardon, Ms Paetongtarn said her father would make that decision himself and the family would back him.
The Department of Corrections reported earlier that Thaksin had four critical ailments -- heart disease, lung disease, high blood pressure and a herniated lumbar disc.