Activists on Monday demanded the Police General Hospital release the latest condition of former prime minister Thaksin Shinawatra, to prove if he deserves to stay there instead of in prison.

Representatives of the Student and People Network for Thailand Reform (SNT) went to the Royal Thai Police Office in Pathumwan district to submit their letter addressed to the national police chief.

The letter demands that the management of Police General Hospital give an update on Thaksin's condition. Thaksin is serving a one-year prison term, but was admitted to the hospital on the first night after he went to prison.

"The Student and People Network for Thailand Reform is of the view that doctors have been unusually silent on his illness after a previous report that he was severely ill and needed specialist doctors and equipment," said Pichit Chaiyamongkol of SNT.

Thaksin was moved from his prison to the hospital on Aug 22 and society wanted doctors at the hospital to clarify his illness, Mr Pichit said. Doctors at Bangkok Remand Prison referred Thaksin to the Police General Hospital on the night of Aug 22, only hours after his return to the country.

"It was evident that Thaksin appeared normal when he arrived in Thailand," Mr Pichit said.

The SNT asked the national police chief to reveal the names of the doctors who were treating Thaksin and order them to elaborate on Thaksin's condition.

Mr Pichit said that on Thursday this week Thaksin will have spent one month at Police General Hospital.

Thaksin, 74, returned to Thailand on the morning of Aug 22 after 15 years in self-exile. He had been convicted and sentenced and charged during his absence.

The same day the Supreme Court ordered he be imprisoned for eight years for the three cases. His jail term was reduced to one year by His Majesty the King.