Kerala police have booked a group of Enforcement Directorate officials on the charge of “applying mental pressure” on gold-smuggling accused Swapna Suresh to falsely implicate chief minister Pinarayi Vijayan.

The crime branch on Wednesday filed an FIR on the basis of an audio clip in which a woman suggests that ED officials had tried to force her to name Vijayan. Police sources said Swapna had confirmed to crime branch investigators that the voice was hers.

The accused ED officials are understood to be based in Kerala but the FIR, filed in Ernakulam, does not name them or say how many they are. It says Swapna faced the coercion during her ED interrogation on August 12 and 13 last year.

Swapna is a key accused in the smuggling of 30kg gold, valued at Rs 14.82 crore, in diplomatic baggage addressed to the attaché of the UAE consulate general in Thiruvananthapuram in July 2020.

A former secretary with the consul general, Swapna had allegedly used her connections with local authorities to help smuggle the contraband from Dubai. Arrested soon after, she has been in the custody of the various central agencies probing the case or in judicial custody.

The 35-second clip was leaked to the media on November 19 last year. It’s not clear who the woman in the tape was talking to, or where and when, nor who recorded it or leaked it.

“What my lawyer told me today is that the statement submitted before the court states that I had gone to the UAE with (suspended IAS officer) Sivasankar in October and did financial negotiations for the CM,” the woman says.

M. Sivasankar, then secretary at the chief minister’s office, was among those arrested in the case. He has since been granted bail.

“They (the investigators) are asking me to ratify that (statement in court) to make me an approver. When I said I would never do that, I was told they would come to jail and force me again,” the woman in the audio says.

The accused ED officials have been booked on the charges of framing people with incorrect documents, fabricating evidence, giving false evidence, abetment and criminal conspiracy. Conviction can bring a jail term of up to seven years.

The crime branch has been probing the tape’s authenticity, the leak and the veracity of the woman’s allegation following a legal opinion from the state director-general of prosecution.

Two policemen deployed for Swapna’s security during the ED interrogation have given written submissions to the police saying they overheard an ED official named Radhakrishnan pressuring Swapna to name the chief minister.

Another prime accused in the case, Sandeep Nair, recently submitted a handwritten letter to a sessions judge in Ernakulam alleging coercion by a “Mr Radhakrishnan”.

“Investigating officer from this agency (ED), Mr Radhakrishnan, told me they won’t oppose my bail plea if I named the Kerala chief minister, some ministers and the son of a senior leader,” Nair, who is in judicial custody, alleged in the letter.

Nair, a BJP worker, said he had been offered a good lawyer and a promise not to oppose his bail application. He alleged harassment in ED custody saying he had been deprived of sleep and “threatened” several times.

The FIR comes at a time the Congress and the BJP have been using the charges against Sivasankar to point a finger at Vijayan.