According to ANI, DMK's Mk Stalin said "IT raids at Chief Secy residence is a disgrace to the state, perhaps for the first time a raid is conducted at a CS's place in TN".
"The raids have commenced at Tamil Nadu Chief Secretary's residence," a senior IT official said.
The searches that began as early as 6:00 AM are on at various places in the state and neighbouring state of Andhra Pradesh.
"A total of 13 premises are being searched," a senior official said, adding the premises connected to Rao's son and other relatives are part of the operation.
It is understood that the official residence of the Chief Secretary in the state capital here has also been brought under the said operation.
Rao, who was appointed the Chief Secretary in June 2016, holds the additional charge of Vigilance Commissioner and Commissioner of Administrative Reforms.
The searches, they said, are related to the department's probe in the biggest haul of cash and gold here post demonetisation, in which over Rs 142 crore unaccounted assets have been recovered so far.
The total seizure in the case is over Rs 170 crore in a single case related to action against sand mining operators in the state and few others including S Reddy, who was also on the panel of a religious shrine body.
The Enforcement Directorate has also registered a money laundering complaint in this case after the tax department shared official documents with the agency.
Raids are being carried out across the country by the Income Tax Department in the wake of the burgeoning fake currency racket post demonetisation.