By Agence France-Presse
The office of Switzerland's attorney general (OAG) confirmed that three people were arrested in the western canton of Vaud last Friday and Saturday, suspected of violating "the prohibition of groups like Al-Qaeda, Islamic State and similar organisations."
They were also suspected of participating in a "criminal organisation", it said.
A fourth man -- reportedly a taxi driver suspected of being an Islamic State recruiter -- was arrested in Geneva on June 14. There was no apparent link with the other three, according to the OAG.
Swiss authorities have not revealed the identities or the nationalities of those arrested.
In the most dramatic case, police swooped on a car outside a busy mall in Aubonne, Vaud on Saturday, in what one onlooker said looked like a scene straight out of an "American movie".
"It was surreal," the witness told the 20 Minutes daily, describing how heavily-armed police had blindfolded and taken the driver away.
Other witnesses told the paper that police had also taken away his passenger, a woman wearing a headscarf and with a child on her lap.
But the OAG stressed Wednesday that all of those arrested were men, without explaining how the woman in the car figured in the case.
It also denied reports that those arrested had been in possession of explosives, insisting in a statement that "no traces of explosives have been found until now."
OAG information chief Andre Marty did however tell the Le Temps daily that the Aubonne arrests were made because it was believed the suspects "might pose an immediate danger."
Police had first arrested another person in Vaud on Friday, and Marty said investigators were now seeking to determine the connection between the three.
The man arrested in Geneva earlier this month was not believed to have any connection with those arrested in Vaud, he said, insisting it would be "a complete exaggeration to talk about the dismantlement of a terrorist network."
Swiss authorities are currently investigating some 60 cases linked to suspected jihadist terrorism, the OAG said, stressing that most of those cases revolve around the spread of jihadist propaganda over the internet.
"Nothing justifies alarmism," it said.