Political activist Jatuporn Prompan has demanded the Department of Corrections (DoC) and the Police General Hospital release footage of closed-circuit television cameras to clear up the public's lingering doubts over the health of former prime minister Thaksin Shinawatra.
Mr Jatuporn said that based on his experiences of being behind bars five times, he knew that every movement by inmates is recorded on CCTV.
For those who fall ill, all procedures regarding their medical treatment and transfers are recorded.
The footage will show if it is true sickness, or a political sickness, he said during the Thailand First programme on Peace TV, a satellite-based channel on Friday.
"People are wondering whether Thaksin is politically sick or if he is really sick. When he returned to Thailand at Don Mueang airport, key figures of the Pheu Thai Party clearly said he was in good health.
"But all of a sudden he fell sick when he was taken to prison.
"The DoC announced he suffers from four critical diseases -- heart disease, lung disease, high blood pressure and a herniated disc.
The prison hospital was very good to quickly detect the four diseases with the use of a stethoscope," said the 57-year-old former chairman of the pro-Thaksin United Front for Democracy against Dictatorship (UDD), or the red shirts.
Thaksin, 74, was sent to prison on Tuesday after returning home after over 15 years of self-exile, following a court appearance the same day.
He was transferred from Bangkok Remand Prison to the Police General Hospital at 12.20am on Wednesday after suffering from chest pains, hypertension and low blood oxygen, according to the DoC.
Pol Lt Gen Dr Sophonrat Singhajaru, the hospital's chief physician, said yesterday his condition improved but he is still fatigued due to his lung condition after he was infected with Covid-19 twice. He is still on oxygen.
On Monday, the hospital will allow the first visit from his family members, he said.
But Mr Jatuporn doubts whether Thaksin is really critically ill and wants to see video footage as proof of the state of his health.
"If he is really critically ill, nobody opposes any special treatment for him. If not, this will be a new problem. There will be intense public scrutiny.
"Those involved will face mounting pressure from society and they will end up in jail," said the former red-shirt leader.