A bomb blew up the car of a popular Bulgarian journalist this evening in Sofia, coinciding with a visit of European Commission President Jose Manuel Barroso and three members of the Commission to the Balkan country, police said.
The explosion caused no casualties but the incident is the latest blow to the centre-right government's efforts to put an end to the climate of impunity in one of the most corrupt EU member states ahead of local and presidential polls on 23 October.
Television journalist Sasho Dikov, known for his critical attitude to the cabinet, said he had never received any threats.
The Organization for Security and Cooperation in Europe (OSCE), which is monitoring the election, said violence against journalists was a growing problem in Bulgaria and called for a swift investigation.
"(I relate the blast) to individuals who think it can be a useful tool in the pre-election campaign," Interior Minister Tsvetan Tsvetanov was quoted as saying by news agency Focus.
The ruling GERB party swept to power in 2009 promising to restore the rule of law and improve Bulgaria's image but has yet to put any major figures behind bars.
It was the latest in a string of small explosions and outbreaks of civil unrest this year, which has highlighted GERB's poor record in improving the economy and cracking down on organised crime.
"The attack is formally against the government, but it is in its essence a very bad signal for the country as a whole," said sociologist Antoniy Galabov.
"(It is meant) to discredit the cabinet and create the feeling that it is not capable of dealing with its task."
Series of blasts
At the beginning of the year, a bomb exploded in front of the office of an opposition newspaper.
The government said at the time the blast, which took place hours before the visit of a group of EU Commissioners, was meant to disgrace the cabinet.
"Violence against journalists is an increasing problem in Bulgaria," Dunja Mijatovic, OSCE representative on freedom of the media, said in a statement.
"The government must increase its efforts to remedy the situation by publicly refuting all attempts to silence journalists and urging law enforcement to bring the perpetrators and masterminds of these crimes to justice."
In July, small explosions rocked the offices of two right-wing opposition parties the day before Brussels issued its annual report on Bulgaria's progress in fighting endemic graft and organised crime.
Two men were arrested shortly after the blasts in front of the parties' offices over suspicions they planted the explosives.
In a joint news conference with Bulgarian Prime Minister Boiko Borisov on Thursday, Barroso praised the government's work and said Sofia needed to continue the fight against crime and to press ahead with the reform of its judiciary system.