Former prime minister Thaksin Shinawatra was not admitted to a VIP room at Police General Hospital and even the air-conditioning where he is staying is not good, authorities said on Wednesday.

Hospital staff had to provide two electric fans to make it comfortable for Thaksin who arrived overnight from Bangkok Remand Prison, said Pol Lt Gen Dr Sophonrat Singhajaru, chief physician at the hospital.

He also denied that the room where Thaksin is staying had a beautiful view. In fact it is next to a glass wall and quite hot, the hospital chief said.

Dr Sophonrat was responding to reports and images shared online, which showed a VIP room that resembled a five-star hotel suite on the 14th floor of the state hospital. Another image showed a view of the Royal Bangkok Sports Club.

Thaksin, 74, returned to Thailand on Tuesday after more than 15 years in self-exile abroad. Within a matter of hours he appeared in court, was sentenced to eight years in prison and taken to the Bangkok Remand Centre.

Prison officials placed him on a medical ward as he was found to be suffering from a variety of ailments, but within a few hours he was on the move again.

Thaksin was found to be suffering from acute chest pain, low blood oxygen and very high blood pressure. Prison doctors decided to move him to Police General Hospital.

The hospital chief also denied a report that another patient had been discharged to clear a room for the billionaire former premier.

Thaksin was said to be feeling slightly better on Wednesday morning. He still has high blood pressure and is being given oxygen. He can communicate but is tired and short of breath, his doctors reported.

Doctors have banned all visitors and are unable to predict how long Thaksin would have to stay at Police General Hospital, Dr Sophonrat said.

The Ministry of Justice said that if Thaksin were to be discharged from Police General Hospital, he would not be referred to any private hospital.

There had been unconfirmed reports earlier that one option was to have Thaksin brought to Praram 9 Hospital, in which the Shinawatra family are major shareholders.