There has been a sixth night of rioting in Sweden's capital, Stockholm, despite police reinforcements being deployed.
Cars were set alight in poor suburbs inhabited largely by immigrants, although the unrest was reportedly not as serious as on previous nights.
The rioting also spread outside the capital for the first time on Friday, with youths torching vehicles and buildings in two towns.
The US and UK meanwhile warned their citizens to avoid affected areas.
The UK Foreign Office advised people to stay away from large gatherings in the Stockholm suburbs of Husby, Hagsatra, Ragsved, Skogas, and to take care and monitor local reports.
The riots began on Sunday in Husby, a deprived, predominantly immigrant area in the north-west of the capital.
It is believed they were sparked by the death of an elderly man nearly a week before, who was shot by police after he allegedly threatened to kill them with a machete.
On Friday, Stockholm's police force was reinforced by specially trained officers from the cities of Gothenburg and Malmo, both of which have seen rioting in recent years.
Parents and community leaders also toured the streets to reason with trouble-makers, and Prime Minister Fredrik Reinfeldt held an emergency meeting.
However, the moves failed to prevent fresh disturbances overnight in four areas.
The BBC's Steve Evans in Stockholm says the disturbances were nevertheless not as serious as those seen previously. According to the fire brigade, there were 70 fires, compared with 90 on Thursday.
Outside the capital, the violence spread to previously unaffected towns, he adds.
In the central town of Orebro, about 25 masked youths set fire to three cars and a school, while in Sodertalje, just outside the capital, an empty building was torched, police said. Suspected arson attacks were reported in Linkoping, south of Orebro, as well.
Police in Orebro were pelted with stones and at least one officer was slightly hurt by broken glass, Swedish media reported.
Our correspondent says there is now a debate in Sweden about immigration.
In the affected areas themselves, some people say the riots are a response to discrimination and relatively high unemployment. Sweden, once a by-word for equality, has seen a widening gap between rich and poor, our correspondent says.
Others argue that the unrest is a simple matter of criminality, where parents failed to exert enough influence on their offspring, he adds.
Gulan Avci, a Swedish MP of Kurdish origin who represents the Stockholm suburb of Bredang, said the rioting was down to a mixture of criminality and disillusioned young people in areas of high unemployment and poor school results.
She told BBC radio that the country's integration policies had not been successful.
"But you can never ever accept violence as a way to show your disappointment with society. These teenagers don't understand they're destroying for themselves their own future, for other people that live in these areas."
"In the short run, the acute thing is to ensure that these neighbourhoods get back to normal everyday life," Integration Minister Erik Ullenhag told the Reuters news agency. "In the long run we need to create positive spirals in these neighbourhoods."