GOTHENBURG, Sweden, July 1 (Reuters) - Swedish caretaker Prime Minister Stefan Lofven expressed outrage on Thursday over the killing of an on-duty police officer, a rarity in the Nordic country, calling it an "attack on our open society" amid growing concerns over gang violence.
The police officer in his 30s was shot and killed late on Wednesday while on duty in Biskopsgarden, a Gothenburg suburb that has been plagued by gang violence in recent years and where police have had an increased presence.
"It is with great sadness and dismay that we received the news that a policeman was shot to death last night," Lofven told a news conference. "We will never back down in the struggle against organised crime."
Sweden held a national minute of silence on Thursday to honour the slain officer.
The crime has shocked a country where fatal attacks on police officers are rare, with three killed in the last 20 years, including Wednesday's victim.
Gang violence has been in the spotlight after shootings and explosives attacks that have sometimes killed bystanders, and has become a political battleground, with left and right each seeking to claim the tougher line.
Experts disagree over the causes of Sweden's gang problem, citing lax laws, segregated urban areas, immigration and an increased drug trade.
Local police said they did not know why the officer had been attacked. They had a description of the shooter but said no arrests had been made in connection with the shooting.
Right-wing opposition leader Ulf Kristersson, who earlier on Thursday abandoned his attempt to form a new government after Lofven lost a no-confidence vote last week, urged Sweden to rally and defeat what he called "domestic terrorists".
A report published this year by the Swedish National Council for Crime Prevention, said Sweden had among the highest levels of fatal shootings in 22 European countries and that no other country had seen as swift an increase as Sweden. (Reporting by Johan Ahlander; Editing by Niklas Pollard and Catherine Evans)
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