The so-called Black Block has come under further police scrutiny after scenes of violence put a stop last weekend to a rightwing political rally held in the capital Bern.
But specialists say the loose grouping of anarchists and extreme leftwing activists does not present a danger to Switzerland's internal security.
Press coverage during the week gave prominence to the rioting against the Swiss People's Party rally and the forces behind it, speculating that demonstrators were shipped in from abroad. But Jürg Bühler of the federal police told swissinfo there was no credence to this theory.
"We have no indication that the demonstration sparked any significant international mobilisation," he said.
There was no organised movement of people from around Switzerland either, according to Bühler. An influx of outside demonstrators is more often seen in connection with international themes such as G8 summits or the WEF in Davos, he pointed out.
Bühler also reckoned it was unlikely that provocateurs were involved. "As a rule it does not take much to stir up the Black Block," he added.
Politicians across the board condemned the violence that disrupted the People's Party rally, held ahead of upcoming federal elections.
However critics have pointed out that the party of the controversial justice minister, Christoph Blocher, had been stoking tensions with its hardline policies, and has been milking the incidents for further political gain.
But despite the dramatic images and headlines generated by the Black Block, they do not constitute a danger to Switzerland's internal security, Bühler concluded.
"This incident must be put into perspective. The groups are weak in numbers and too badly organised and positioned to achieve their goals," he said.
Young and apolitical
Political scientist and author Mark Balsiger was one observer of the events in Bern's old town of Bern last weekend.
"I would guess that most of the violent protestors were aged between 16 and 20 and were apolitical," he told swissinfo.
Balsiger assumed that most of the participants went along for kicks and he categorised them as followers. "Not all of them were semi-professional demonstrators kitted out with ski glasses, scarf, black hat and stones," he said.
But Balsiger said he did not wish to completely depoliticise the demonstrators and thought there were also anarchists involved. Others were probably provoked by the "People's Party's very aggressive advertising style" in recent months.
At least 20 people were injured and dozens detained for questioning after the event. The activists also destroyed the infrastructure set up in front of parliament for the People's Party rally.
Bühler said this disruption and damage to property caused uncertainty amongst the population and incurred expenses for the authorities.
But the city of Bern apparently knew what to expect beforehand and has been criticised for failing to act properly. The federal police apparently did warn the authorities of possible violence.
"It is in our interest to pass on all useful information to safeguard internal security so that the police action can be as successful as possible," Bühler added.
The Black Block is the name of an underground grouping of extreme left-wing militants that keeps a low profile when not involved in violent demonstrations.
There are other Black Blocks around the world, including in North America, and they have been involved in rioting at G8 summits.
The Swiss Black Block's members have taken part in three violent incidents over the past three months, in Geneva, Lausanne and most recently Bern. They are also a regular "highlight" on May 1 in Zurich.
Some reports say the leadership are veteran activists based in Zurich aged over 50. An estimated 2,000 people are associated with the Swiss Black Block movement.