Recurring allegations that the Narendra Modi government unleashes the central agencies on witch-hunts in Opposition-ruled states when elections are round the corner found a “voice” on Thursday when a leaked audio clip surfaced overnight in Kerala.

In the audio tape, a key accused in a gold smuggling case accuses unidentified investigators of coercing her to name and implicate chief minister and CPM leader Pinarayi Vijayan.

The voice has been confirmed as that of Swapna Suresh, a former UAE consulate employee who had last year joined a project under the Kerala government’s Space Park, allegedly with the help of an IAS officer who virtually ran the chief minister’s office. Both Swapna and the IAS officer, M. Sivashankar, are in judicial custody after being arrested by central investigators.

In the tape, Swapna does not name the agency that allegedly tried to force her to name chief minister Vijayan, nor is it clear who she is speaking to.

Swapna was arrested by the Enforcement Directorate. Three central agencies — the ED, the customs department and the National Investigation Agency (NIA) — are probing the gold smuggling case and have interrogated her.

In the audio tape, Swapna is heard accusing the investigators of offering to make her an approver if she implicated Vijayan in the case.

“They did not allow me to read the statements since sixth (not clear which month)… (but) asked me to sign after quickly scrolling (the pages),” Swapna is heard saying in the 35-second audio clip, which surfaced late on Wednesday.

Swapna said: “What my lawyer told me today is that the statement submitted before the court states that I had gone to the UAE with Sivashankar in October and did financial negotiations for the CM.

“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.”

Deputy inspector-general of prisons and correctional services Ajay Kumar, who met Swapna at the women’s jail in Thiruvananthapuram on Thursday, told reporters she had confirmed it was her voice in the audio clip.

“It was not (recorded) in the jail for sure. She said it was from somewhere else during a casual chat. She has been to a lot of places (as part of the investigation),” Kumar said.

There had been no official word till late evening from the Enforcement Directorate, which rarely comments on such matters.

Swapna is one of the main accused in the attempt to smuggle 30kg of 24-karat gold from Dubai in a diplomatic bag addressed to an official in the consulate-general of the UAE in Thiruvananthapuram.

The scandal has pushed the ruling CPM on the back foot at a time the state is gearing for local body elections next month. The Assembly elections are scheduled in the summer.

The CPM state secretariat termed the contents of the audio clip “extremely serious”.

“The details about misusing central agencies to topple the state government by targeting the chief minister are extremely serious in nature,” the party said in a statement.

“Enticing and pressurising the accused by offering to make them approvers is an open challenge to the rule of law and democratic principles.”

Kerala recently joined an increasing number of Opposition-ruled states that have scrapped their general consent to the CBI taking up cases within their territory.