Dusan Miljus, of the Jutarnji List daily, was jumped on by two men on Monday evening. He was taken to hospital with concussion and a broken arm.
"They had helmets on so I could not see their faces and it all happened very quickly," Miljus, 47, who has covered the local crime scene for 20 years, told the daily.
Miljus reported getting anonymous threats to the police earlier this year. An obituary with his name and photograph was published in another daily, Vecernji List. The daily apologised and said it had been a "procedural mistake".
Davor Butkovic, a Jutarnji List editor, said the assault was an attack on free press in the European Union candidate country.
"Newspaper publishers have been exposed for years to threats from criminal organisations... who have their people infiltrated in the entire state establishment," he told Reuters.
"Hence the police inefficiency and inability to prevent such attacks or start a serious fight against organised crime."
A Zagreb city official in charge of road-building was attacked by men wielding baseball bats last month after he exposed corruption in the city.
The fight against corruption and organised crime, as well as reforms of the judiciary, public administration and economy, top the list of requirements Croatia must meet before joining the EU, possibly in 2011.
Güncelleme Tarihi: 03 Haziran 2008, 12:38