Newspaper editor Ivo Pukanic and a colleague were killed by a car bomb
Croatian police have arrested 10 people in connection with last week's mafia-style murder of a high-profile editor.
A police official said elite forces were used to apprehend the suspects, whom he described as "extremely dangerous members of criminal circles".
He declined to comment on reports that two of those arrested were Serbs.
The police chiefs of Croatia and Serbia are meeting to step up co-operation against organised crime, which operates across the border of both countries.
On 23 October a car bomb in the capital Zagreb killed Ivo Pukanic, editor of the weekly newspaper Nacional, alongside the paper's marketing director, Niko Franic.
The murder is one of a series of mafia-style killings that prompted Croatia's new justice minister to declare a crackdown against organised crime on Wednesday.
Under new legislation he announced to parliament, special courts would be set up to fast-track such cases, witness protection would be improved, and convicted criminals would have their property confiscated.
Tackling organised crime is one of the key criteria Croatia must meet on its path towards membership in the European Union, which Zagreb hopes to join by 2010.