Geneva, which borders France and is home to the UN's European headquarters, ratcheted up its security Thursday after receiving information from the Swiss government about suspicious individuals in the area.
The region remains at alert-level three out of five, the cantonal government told AFP early on Friday.
"For now, there is no change to the security situation," said spokeswoman Emmanuelle Lo Verso, who on Thursday said police were investigating "a specific threat", and were "actively searching" for suspects.
Several Swiss media reported that the intelligence originally came from the United States.
The Le Temps daily cited an unnamed source close to the case as saying US intelligence had identified three jihadist cells, in Toronto, Chicago and Geneva, and that a picture of four individuals had been circulated to police across the canton on Wednesday.
"We do not know their names, we do not know where they came from," the source told the paper.
"They apparently are using noms de guerre."
The office of Switzerland's top prosecutor meanwhile said in a statement late Thursday that it had opened a probe into "a terrorist threat in the Geneva region," targeting unnamed individuals over possible support for banned groups, including "Al-Qaeda and the Islamic State".
"The main goal is to prevent a terrorist event," it added.
In Geneva, which is almost entirely surrounded by France, authorities said 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 13th gun and suicide bombing attacks that left 130 dead.
Pierre Maudet, in charge of security issues in the Geneva government, told Le Temps the security level would remain high "as long as this specific threat has not disappeared."
But he stressed that the security alert in the region was not comparable to the lockdown seen in Brussels last month.
"We cannot say that an attack was averted here today," he told the paper late on Thursday.
At the United Nations complex in Geneva, which was evacuated and searched late Wednesday, security remained significantly higher than usual Friday morning, although there seemed to be fewer guards visibly carrying sub-machine guns than the day before.
"There is no specific threat to the UN in Geneva or its personnel," UN spokesman Michèle Zaccheo told reporters, adding that the security measures were "commensurate with what is happening in the region".