GENEVA -- Two Syrians arrested in a vehicle containing traces of explosives have not been clearly linked to four men with suspected ties to the Islamic State of Iraq and Syria who are wanted by Swiss authorities, the Geneva prosecutor said Saturday.

The arrests of the two Syrians on Friday came amid stepped-up police patrols in Geneva. Authorities raised the security vigilance level and announced a hunt for at least four suspects allegedly linked to ISIS who were believed to be plotting a "specific" attack in the city.

Geneva prosecutor Olivier Jornot spoke to reporters after Switzerland's Attorney General's office and Federal Police Office announced criminal investigations against the two Syrians on suspicion that they had violated laws on making and transporting explosives and toxic gases and a ban on links to militant groups like al Qaeda or ISIS.

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Amid concerns that the four fugitives might have accomplices, Jornot said: "No link has been established in the different cases."

Clarifying an earlier official statement, the prosecutor said no toxic gas - only traces of explosives - were found in the Syrians' vehicle, which they told police they had only recently obtained.

He said the two Syrians spoke no French and were believed to have been recent arrivals in Switzerland.

The widened dragnet also led authorities to detain another suspect, a Swiss man found with an "absolutely impressive arsenal" including automatic weapons. He was a suspected far-right "survivalist" who also possessed a Nazi flag, Jornot said, adding that arrest was not related to the hunt for the four suspected jihadis.