BANGKOK: Thailand's former Prime Minister Thaksin Shinawatra was moved to hospital overnight, officials said on Wednesday, over concern about his heart and high blood pressure on his first night in jail following his historic return from self-exile.

The latest condition of 74-year-old Thaksin, the billionaire founder of the populist juggernaut Pheu Thai, was not clear on Wednesday and his representatives did not immediately respond to a request from Reuters for comment.

The Corrections Department said in a statement Thaksin had felt chest tightness and high blood pressure and he was referred to Bangkok's police hospital at around 2 a.m. on Wednesday.

Thaksin made his homecoming on Tuesday and was escorted to jail in dramatic scenes that stole the spotlight from political ally Srettha Thavisin, who was elected prime minister in a parliamentary vote later in the day.

The Pheu Thai Party's Srettha was confirmed as prime minister having received royal endorsement, a parliament official said on Wednesday.

Police said Thaksin was hospitalised because the prison was unable to guarantee he would get the right care.

"The prison has assessed the situation and saw that it lacks doctors and medical equipment that can take care of the patient," Assistant National Police Chief Lieutenant General Prachuab Wongsuk told Reuters.

The Supreme Court confirmed on Tuesday that Thaksin would have to serve eight years in prison after convictions for abuse of power and conflicts of interest.

Thaksin was accompanied by eight prison guards when he was transferred during the night, Ayuth Sintoppant, director general of the Corrections Department told Reuters.

The return of Thailand's most famous politician was met with celebrations by his supporters and with blow-by-blow media coverage of arrival in Bangkok on his private jet, and his transfer to prison soon after.

His return and Srettha's surprisingly smooth ascent to the top job will add to speculation that the influential Thaksin had struck a deal with his foes in the military and political establishment for his safe return and, possibly, an early release from jail. Thaksin and Pheu Thai have denied that.