But two car bombs in three days this week have shattered not only the summer calm but Sweden's self-confidence.

The bombs, which seriously injured a journalist, his young son and two policemen, have also triggered a heated debate on whether the liberal principles that underpin Sweden's political culture can withstand threats from extremists.

"People think of this as a secure country, but we have never dealt with car bombs before," said Margareta Linderoth, the deputy director of Sweden's security police.

"In the past if there was extremist violence it was in the streets and against foreigners or gay people, not against political society."

The first bomb, which exploded on Monday and is believed to have been planted by neo-Nazis, was aimed at a journalist who has been investigating the extreme right. It went off in his car, outside his home.

The reporter, who writes under the pseudonym Peter Karlsson, and his eight-year-old son are still in hospital. The family was under police protection because of threats from far-right activists.

It was the second attack in four weeks linked to neo-Nazis. At the end of May two policemen were shot dead when they stopped a car near Kisa, south of Stockholm, after a bank robbery. Two of the three men charged with the murder had links with the country's largest neo-Nazi group, the Nationalsocialistisk Front.

Then, in the early hours of Thursday this week, two policemen were seriously injured while responding to a tip-off about a stolen car in southern port of Malmo. No organisation has claimed responsibility for either of the bombings. Some suspect that the two may have been coordinated, others that the second my have been the work of the Hells Angels, prominent in the area.

"It is too early to tell whether the first bomb is related to the second," said Stieg Larsson, an editor on the anti-fascist magazine Expo.

"But in itself the first bomb represents a dramatic change in the tactics of the far right. This was attempted murder. It called for planning and a certain amount of expertise."

Many are now saying that if the extremists have changed their strategy it is time for Swedish society to alter its stance on how to deal with them.

"As a country we have been extreme in our defence of both freedom of speech and generally offered considerable protection to minorities," said a lecturer in political culture at Stockholm university, who refused to be named. "That has created some contradictions. You can be arrested for saying Sieg Heil but not if you defend Nazi ideas in text."

Liberal Swedes are baffled why a country that used to be considered one of the world's most ethnically and socially homogeneous should have changed so dramatically. As the lecturer put it: "Now we are multi-racial. But our self-image of what those changes mean for a liberal, western nation has been slow to catch up."

Any visitor expecting Stockholm to be an Aryan enclave is in for a shock. About 12% of Swedes are classified as immigrants, although since the vast majority of those are Finns and Danes precise figures on the non-white population are difficult to come by. But the capital seems to be racially far more diverse than such central European cities as Vienna and Zurich, and far more socially integrated than Paris or Milan.

So the tradition of dealing with neo-Nazism by debate, the tabloid Aftonbladet suggested, is a luxury the country can no longer afford.

"Nazi violence has stepped up a level from being directed at individuals to attacks on society and democracy," the paper said in an editorial. "The Nazi threat must be taken more seriously."

But it must also be put into perspective. In a country of about 9m, active membership of neo-Nazi organisations numbers no more than 1,000, divided among several groups who spend a lot of time fighting one another.

While their recent attacks have been more dramatic than in previous years, there have been fewer of them.

In fact, where the far right has really made a difference in Sweden is neither at the polls nor on the streets but on the turntables. The country that once boasted Abba as one of its main exports is now one of the main suppliers of white supremacist music to the rest of the world.

This transition from glam rock and gay anthems to skinheads and the moon stomp is the most vivid example of Sweden's painful and delayed meeting with the uglier aspects of the late 20th century.

"It really started with the murder of Olaf Palme," said Niclas Lindstrand, a journalist who covers the far right for the national daily Dagens Nyheter. When their prime minister was shot while walking back from the theatre in 1986, Swedes took years to recover.

"People thought this couldn't happen here, but then lots of things started happening that we didn't think could happen here," Mr Lindstrand said.

"There was the recession in the early 90s. We were hardly used to unemployment at all: all of a sudden it was up to 1930s levels. And with the recession came the Nazis and a general feeling that there were two many immigrants."

In the past few years, people's confidence in the political elite and its liberal legacy has started to erode."Politicians and citizens here really did use to interact at a very close and personal level," Mr Lindstrand said.

"But that is over now. There aren't too many leaders Swedish people really trust any more. There was that sense of common purpose and shared values.

"Nobody believes that any more. It's just the place where we happen to be."