"The police interview began on Monday evening and was suspended late at night. It continued this morning," Jelavic's lawyer Milenko Umicevic confirmed to media.

Umicevic would not reveal what the interview was about, only saying that his client was not charged with any crime and that he expected him to be released later in the day.

Police said two weeks ago they wanted to interview Jelavic as part of Operation Shock 3 in which two suspected attackers on journalist Dusan Miljus and businessman Josip Galinec had been arrested. The attacks occurred in 2008.

Jelavic was arrested at Zagreb's Pleso airport shortly after 4 pm on Monday after flying in from Sarajevo.

Umicevic said he had informed the police last week that his client was returning to Zagreb and would respond to the summons for an interview with the police. The lawyer said he believed yesterday's arrest was therefore unnecessary.

In order to identify the people who commissioned the attacks on Miljus and Galinec, the police interviewed a number of people with ties to the Zagreb underworld. Suspects Djordje Vuletic and Darko Dakic are currently in 30-day custody for alleged attempted murder of Miljus and Galinec.

In the late 1990s, Jelavic, Vuletic and Zoran Pripuz were arrested on suspicion of forming a criminal organisation which was allegedly led by Jelavic. Jelavic was charged with murder of an innocent bystander and two attempted murders, and, together with Pripuz, with incitement to murder. The court ruled that there was no evidence to prove the existence of a criminal organisation and found five of the 12 accused guilty of drug trafficking and attempted murder. Jelavic, Pripuz and Vuletic were among those acquitted.