Barisic, a former treasurer of the ruling Croatian Democratic Union (HDZ), is the only suspect in this case, and his lawyer could not reveal any more details, citing confidentiality.
According to unofficial information, Barisic is suspected of having unlawfully secured marketing and advertising projects for the Fimi-media company, owned by his friend Nevenka Jurak, in state-run companies - the INA oil company and the Croatia Osiguranje insurance firm.
Barisic was dismissed as the HDZ treasurer in late January after the party's leader, Jadranka Kosor, said that he had not been doing his job in the party since she took over from Ivo Sanader.
When asked about Barisic's possible dismissal as head of the Customs Administration, Prime Minister Jadranka Kosor said today that all state bodies must do their job.
When those who do their job inform me about arguments I will make decisions just as I have done so far, Kosor said, adding that the anti-corruption drive would continue relentlessly.
Regardless of a person's name and political affiliation, the struggle against corruption and crime must be conducted constantly and on a daily basis, she added.
"The anti-corruption drive is related to the completion of (Croatia's European Union accession) negotiations, but it must be conducted for the sake of us all because it is a struggle for human rights," she said.