"The relevant agencies have assessed that his life is in danger, so he has been accorded police protection," Seric told Croatian Television in an interview.

Mravak, former deputy prime minister Damir Polancec and the former CEO of the light metals factory TLM, Ivan Kostan, are suspected of defrauding HEP of 600 million kuna.

Seric welcomed a request by the national anti-corruption office USKOK for an investigation into the unauthorised disclosure of portions of a confidential deposition by one of the suspects in the HEP case.

USKOK has said that the leakage of the confidential document to the media is a crime of disclosure of official secret.

Mravak was released from investigative custody 10 days ago.