More than dozen cars have been burned and many arrested after overnight violence in suburban districts of Stockholm where many young people had been on a rampage for more than five days.

Police say that overnight violence was less intense than previous nights but as many as 25 cars had been burned, while one  police officer was slightly injured.

Stockholm police spokesman Kjell Lindgren said Saturday 19 people were detained on the sixth straight night of violence, but there had been no hurling of rocks against officers as in previous days.

In Orebro, some 163 kilometres west of Stockholm, a car and a school were set on fire, and a police station was attacked. An officer suffered an eye injury when rocks were hurled at the patrol car he was in, local police said. It was unclear whether the violence had any links to the recent events in Stockholm.

Police got reinforcements from colleagues in larger cities such as Gothenburg.

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Sweden has experienced the biggest surge in inequality of any Organization for Economic Cooperation and Development country over the past 25 years. (Fredrik Persson/Reuters)

The unrest in the Stockholm suburbs, some of which are predominantly populated by immigrants, was sparked by perceived police brutality after officers shot and killed a knife-wielding man who had locked himself in his apartment. Some residents accused police of unnecessary violence when trying to arrest him and others have said that officers, who reacted to the violence on the streets, were allegedly heard to have uttered racist slurs.

For some, the real reason for the unrest is the high unemployment and isolation of youths in the southern and western Stockholm suburbs where the violence occurred -- ones who see little future for themselves or access to Sweden's prosperity

Despite Sweden's high living standards and its egalitarian ways, the country has seen the biggest surge in inequality of any Organization for Economic Cooperation and Development country over the past 25 years, according to a recent OECD report.

The difference is striking between native Swedes and the fast-growing immigrant population.

In Husby, the neighbourhood west of Stockholm where the violence started Sunday, around 80 per cent of the 11,000 residents are either first or second generation immigrants.