According to a statement from the Ministry of the Interior, Stjepan Hucika and Stjepan Juricko arrived at the Bregana border crossing around 10 a.m. on Sunday and were escorted in the company of their lawyers to a police station in Samobor, 15 kilometres west of Zagreb, for an interview.
They were questioned by crime police and representatives of the Office for the Suppression of Corruption and Organised Crime (USKOK).
The statement said that the two men were not arrested, and that the possibility of pressing charges against them for aiding a fugitive from justice would be considered at a later date.
Hucika and Juricko were in the company of runaway tycoon Hrvoje Petrac last Wednesday when they were arrested by the Greek police in the port of Igoumenitsa aboard a ferry bound for the Italian port of Ancona.
The Greek police let the two men go because they were not on Interpol's wanted persons list, while Petrac was sentenced by a Greek court to five months in jail for entering Greece on a fake passport.
After their clients were released from the Samobor police station at about 2 p.m. on Sunday, lawyers for Hucika and Juricko said that the two men had travelled to Greece to persuade Petrac to turn himself in to Croatian authorities.
The lawyers said that USKOK decided not to prosecute Hucika and Juricko, who declined to answer reporters' questions after the interview in the police station.
Petrac has been on the run since the kidnapping of a Croatian army general's teenage son in February 2004. A year later a Zagreb court found that he had masterminded the abduction and sentenced him in absence to six years' imprisonment.
Petrac is also seen as being a member of a network of supporters of the most wanted Croatian fugitive, General Ante Gotovina, who is sought by the UN war crimes tribunal in The Hague.
Gotovina has been in hiding since July 2001 when the tribunal indicted him for war crimes committed during Operation Storm, the Croatian military offensive that crushed the Serb insurgency in central Croatia in the summer of 1995.