Former Tamil Nadu Chief Secretary P Rama Mohana Rao, whose house and office were searched by Income Tax officials in connection with a tax evasion probe post demonetisation, was on Saturday admitted to a private hospital in Chennai after he complained of chest pain.

Rao complained of pain in his chest at around 1am at his residence and was rushed to Sri Ramachandra Hospital in suburban Porur.

Hospital sources said that "he (Rao) complained of chest pain and was immediately attended to by doctors."

"Presently, he has been kept under observation and his vitals are being monitored." the sources said.

On December 22, Rao was replaced from the top post by Additional Chief Secretary Girija Vaidyanathan.

Rao's removal comes after I-T searches at his Anna Nagar residence, besides the premises of his son and some relatives, prompting the opposition parties in the state to seek his removal.

On December 21, Rao's house and office were searched by Income Tax officials, who claimed to have recovered Rs 30 lakh cash in new notes and 5 kg of gold besides getting "disclosure" about Rs five crore of unaccounted income.

The raids were carried out at 15 places, including the office and the residence of Rao, his son Vivek and some relatives in Chennai and Chittoor in neighbouring Andhra Pradesh, IT sources had said.