A senior Kerala IAS officer was questioned for over nine hours by Customs officials on Tuesday in connection with investigations into the smuggling of 30 kg of gold through diplomatic channels in the UAE consulate in Thiruvananthapuram.
It has been alleged by the opposition that the bureaucrat, M Sivasankar, has links to the accused in the gold smuggling case.
Call records leaked to the media by unidentified sources show several calls purportedly made by Sarith, one of the key accused, to Mr Sivasankar.
Prior to this, the IAS officer, who was removed as Principal Secretary to Chief Minister Pinarayi Vijayan, had been linked to another key accused, Swapna Suresh, by the opposition.
The two - Sarith and Swapna - were earlier employed by the UAE consulate.
The Chief Minister, who has been targeted by the opposition for alleged attempts by his office to shield the accused, said Mr Sivasankar's call records would be further probed by the Chief Secretary and the Additional Chief Secretary of the finance department.
The leaked records reportedly showed that Sarith, a key accused who has been arrested by the Customs (Preventive) Department, called Mr Sivasankar at least 14 times over the past three months.
On Mr Sivasankar's alleged role in the case, the Chief Minister said there were, for now, insufficient grounds to proceed against him.
"Other than the link with the woman, no other grounds are there to suspend him now. A government cannot take action based on the figment of imaginations. Let the probe be completed, " he said, in response to opposition demands that he be suspended.
The leaked call records reportedly also showed calls made to a Kerala minister, KT Jaleel, by accused Swapna Suresh.
The minister, however, has said: "I spoke to Swapna after being asked to do so by the Consulate General regarding distribution of food aid".
The minister said he knew Swapna Suresh since she had organised events at the UAE consulate, including one during the Sharjah ruler's visit.
The accused in the case are former consulate staff who were allegedly retained on "request basis". Ms Suresh also secured a contract job through a firm linked to the state IT department, allegedly using fake certificates.
The Chief Minister has said the issue of fake certificates is also being probed.
Swapna Suresh and Sandeep Nair, the two key accused, have been remanded to NIA custody.
On Friday the NIA registered an FIR (first information report) under UAPA (Unlawful Activities (Prevention) Act) and took over the case.
The central agency said initial inquiries had revealed that proceeds from the smuggled gold may have been used to finance terrorism in India.