The four suspects, whose identity the police did not reveal, were released after they were interrogated and after the police raided their flats and temporarily seized documents and other materials discovered there.
An unnamed source close the police said that the arrested persons were Zeljko Dilber from Zadar, Ante Zoni Maksan from Pakostane, Zdenko Rincic from Zagreb and Zeljko Matuzan from Velika Gorica.
The Interior Ministry said that the police established that two of the arrested persons had committed the crime of illegal possession and arms and explosive devices and that criminal charges would be pressed against them.
According to unofficial sources, the two men are Dilber and Maksan.
Ministry officials said that the investigation, which is part of the search for General Gotovina, would continue.