Swiss authorities say two Syrians have been arrested in Geneva on suspicion of transporting "explosives and toxic gases" as part of a probe into suspected jihadists a month after the Paris attacks.
The two suspects arrested on Friday are accused of the "manufacture, concealment and transport of explosives and toxic gases", the federal prosecutor's office said in a statement on Saturday.
They are also under suspicion of violating Swiss law prohibiting "groups like al-Qaeda, Islamic State and similar organisations", it added.
Geneva prosecutor Olivier Jornot told a news conference on Saturday that the two men had Syrian passports and only recently came to Switzerland. They spoke Arabic, he added.
He sidestepped questions on whether they were on visas allowing them to circulate freely through the visa-free Schengen zone.
Several Swiss media reported on Friday that two people had been arrested in the Geneva region and that traces of explosives were found in their car but the authorities only confirmed the development on Saturday.
The office of the Swiss attorney general said on Saturday the pair were arrested in conjunction with "a second criminal proceeding concerning a terror alert in the area of greater Geneva."
The authorities announced a first probe relating to a "terrorist threat in the Geneva region" on Thursday, prompting the region to raise its alert level to three on a five-point scale.
Armed police were deployed at sensitive locations across the city, which borders France and is home to the United Nations' European headquarters.
The Le Temps daily on Friday cited an unnamed source close to the case as saying the Swiss had received a tip-off from US intelligence about a jihadist cell in Geneva.
Pictures of four individuals suspected of links to the Islamic State group, which claimed last month's Paris attacks, were published by media across the country.
Authorities in Geneva had said that the search for possible extremists was being conducted "in the context of the investigation following the Paris attacks".
But multiple sources, who requested anonymity, said there did not appear to be a direct link with the coordinated November 13 gun and suicide bombing attacks that left 130 dead in the French capital.