The car bomb exploded outside the newspaper's offices
A car bomb in the Croatian capital Zagreb has killed Ivo Pukanic, the owner of a leading weekly newspaper, and his colleague.
Mr Pukanic, 47, was killed with Nacional weekly newspaper's marketing executive, Niko Franic, in the blast outside the newspaper's premises.
There is no indication who was behind the attack, which occurred in central Zagreb at about 1820 (1620 GMT).
The city has been gripped by a wave of violence this year.
President Stipe Mesic said the bomb, which was reportedly planted underneath Mr Pukanic's Lexus, meant "terrorism has become a fact on the streets of our capital".
"The state is faced with an unprecedented challenge from the criminal circles," he said. "Now it is them or us... rule of law and safety of citizens against criminals, terrorists and mafia."
Nacional is an investigative paper that often exposes corruption and human rights abuses. Mr Pukanic, who was also the paper's editor-in-chief, had spoken out about a plot to assassinate him earlier this year.
Spiralling crime rates
Croatian Prime Minister Ivo Sanader vehemently and resolutely condemned the attack, and told a news conference that he would not allow "Croatia to become Beirut".
"This is no longer merely a fight against organised crime," he said. "This is something all of us in Croatia will rise up against."
Mr Pukanic had spoken about a plot to assassinate him earlier this year
Thursday's car bomb followed a string of attacks in Zagreb that have been linked to organised crime, says the BBC's Balkans correspondent Helen Fawkes.
Earlier this month the daughter of a prominent Croatian lawyer was shot dead, sparking public outrage.
Shortly after that killing, Mr Sanader sacked his interior and justice ministers, as well as the head of the national police, in response to the spiralling crime rates.
The move came amid fears that rising violence could threaten Croatia's success during EU accession talks next year, correspondents say.
Croatia hopes to complete negotiations for entry in 2009 and to become the 28th EU member in 2011.
A crucial European Commission progress report is due to be released next month.
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