Firemen extinguish a burning car in Kista

Pushed to the limit: A fireman extinguishes a burning car in Stockholm. Photo: AFP

Stockholm has experienced a sixth straight night of riots, with cars torched in several immigrant-dominated suburbs.

Nearly a week of unrest, which spread briefly on Friday night to the medium-sized city of Oerebro, 160 kilometres west of Stockholm, has put Sweden's reputation as an oasis of peace and harmony at risk.

The unrest has also sparked a debate among Swedes over the integration of immigrants, many of whom arrived under generous asylum policies and now make up about 15 per cent of the population.

A car was engulfed in flames before firefighters arrived in the Stockholm district of Tensta on Friday night. Cars were also incinerated in three other areas of the capital, according to the Swedish news agency TT.

''I've never before taken part in anything that lasted so long and was spread over such a wide area,'' police spokesman Lars Bystroem told TT.

Another official said earlier Stockholm police were about to receive reinforcements from Gothenburg and Malmo, Sweden's second- and third-largest cities, but declined to disclose how many would arrive.

In the city of Oerebro, police reported a fire at a school as well as several cars ablaze, but quiet had returned about midnight.

About 200 right-wing extremists were reported to have been crusing around Stockholm suburbs in their cars late on Friday but intense police surveillance apparently prevented any kind of serious violence.

The nightly riots have prompted Britain's Foreign Office and the US embassy in Stockholm to issue warnings to their nationals urging them to avoid the affected suburbs.

Firefighters were sent to 70 fires on Thursday night, extinguishing torched cars, rubbish skips and buildings, including three schools and a police station, the fire department wrote on Twitter.

AFP