Several Stockholm suburbs experienced a fourth night of unrest on Wednesday night (May 22) with youths setting fire to cars and throwing stones at police and fire fighters.

Since the violence started in Husby in northwestern Stockholm on Sunday evening, cars have been torched and police attacked in suburbs of Sweden's capital.

The riots spread from Husby to other poor Stockholm suburbs on Wednesday as groups of youth pushed through the streets throwing stones, breaking windows and setting cars alight.

The riots appear to have been sparked by the police killing of a 69-year-old man wielding a machete in the suburb of Husby this month, which prompted accusations of police brutality.

After decades of practising the "Swedish model" of generous welfare benefits, Stockholm has been reducing the role of the state since the 1990s, spurring the fastest growth in inequality of any advanced OECD economy.

While average living standards are still among the highest in Europe, successive governments have failed to substantially reduce long-term youth unemployment and poverty, which have affected immigrant communities worst.

Some 15 per cent of the population are foreign-born, and unemployment among these stands at 16 per cent, compared with 6 per cent for native Swedes, according to OECD data. Youth unemployment in Husby, at 6 per cent, is twice the overall average across the capital.

While many of the immigrant population are from Nordic neighbours closely tied to Sweden by language or culture, the debate has tended to focus on poor asylum seekers from distant war zones.

Among 44 industrialised countries, Sweden ranks fourth in the absolute number of asylum seekers, and second relative to its population, according to U.N. figures.

Presented by Adam Justice