Thiruvananthapuram, Jul 15 (IANS): Kerala Chief Minister Pinarayi Vijayan's former Secretary and IAS officer M. Sivasankar was grilled for 9 hours by the Customs in the gold smuggling case.

Sivasankar had arrived for questioning at the Customs office on Tuesday evening and was let off only around 2.15 am on Wednesday. He is set to be called again by the Customs and also the National Investigation Agency (NIA) which is also probing the case.

A three-member team of Customs officials had gone to Sivasankar's house on Tuesday to serve a notice upon him. Sivasankar, present at the house, said he was ready to appear before the officials during the day itself for questioning and did so.

Swapna Suresh, a former employee of the UAE Consulate, here and employed with the IT Department, of which Sivasankar was incharge, and three others were booked by the NIA for allegedly facilitating smuggling of 30 kg gold in diplomatic baggage to Thiruvananthapuram from Dubai on July 5.

Sivasankar ran into trouble after his alleged links with Swapna surfaced. Sivasankar has reportedly admitted to the Customs that he and Swapna were friends.

She was on the run after the arrest of her friend and former colleague P.S. Sarith by the Customs.

Later, it was revealed that Swapna and Sivasankar were close and had attended several Kerala government events. Vijayan removed him both as his Secretary and incharge of Information Technology Department though he ruled out his suspension on Tuesday.

Meanwhile, reports of the role played by Swapna's husband and another person employed under Sivasankar have surfaced.

The NIA, which had taken over the case on Friday and filed a FIR against the accused under the Unlawful Activities (Prevention) Act, arrested Swapna and Nair from Bengaluru on Saturday for alleged role in the Kerala gold smuggling case.

It brought them back to the state on a transit remand and presented them at an NIA court in Kochi, which sent them to the agency's custody.