Rioters have lit fires and stoned emergency services in the suburbs of Stockholm for the third night in a row after a man was shot dead by police.
Incidents were reported in at least nine suburbs of the Swedish capital and police made eight arrests.
On Sunday night, more than 100 cars were set alight, Swedish media report.
Police in the deprived, largely immigrant suburb of Husby shot a man dead last week after he reportedly threatened to kill them with a machete.
The founder of a local youth group told Swedish media the riots were a reaction to "police brutality".
On Tuesday night, cars were torched in western and southern Stockholm, and stones were thrown at police officers and firefighters. One area affected, Rinkeby, saw similar rioting in 2010.
Kjell Lindgren of the Stockholm police told Aftonbladet newspaper that the unrest had spread from the original rioting in Husby.
"It feels like people are taking the opportunity in other areas because of the attention given to Husby," he said.
Earlier on Tuesday, Prime Minister Reinfeldt said: "We've had two nights with great unrest, damage, and an intimidating atmosphere in Husby and there is a risk it will continue.
"We have groups of young men who think that that they can and should change society with violence. Let's be clear: this is not okay. We cannot be ruled by violence."
More than 80% of Husby's 12,000 or so inhabitants are from an immigrant background, and most are from Turkey, the Middle East and Somalia.
However, local people accused the police of racism.
Rami al-Khamisi, a law student and founder of the youth organisation Megafonen, told the Swedish edition of online newspaper The Local that he had been insulted racially by police. Teenagers, he said, had been called "monkeys".
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