Jailed former Thai prime minister Thaksin Shinawatra underwent orthopaedic surgery on Monday and is recovering in an intensive care unit at the Police Hospital in Bangkok.

Thaksin underwent five hours of surgery, starting at 9am, said deputy permanent secretary for justice, Sahakarn Phetnarin. He assigned Bangkok Remand Prison chief Nassathee Thongplad to inspect the proceedings and ensure continuing care for Thaksin.

His doctors decided to perform the urgent procedure after reviewing results of CT and MRI scans conducted last week, Sahakarn said.

Thaksin, 74, returned to Thailand in August, ending his self-imposed exile and was immediately taken to Bangkok Remand Prison on corruption convictions. He was, however, transferred to the Police General Hospital a few hours after being incarcerated.

One of his daughters claims that he had another operation last month, but declined to give details.