Geneva security officials said on Thursday that they had raised the alert level in the city and were looking for suspects in connection with investigations into the November 13 Paris attacks.
A security guard at the United Nations in Geneva told Reuters Swiss authorities were searching for four people believed to be in the city, which is close to the French border, or nearby. Another guard said the UN compound was on maximum alert.
"In the framework of investigations carried out following the Paris attacks, at the international and national level, Geneva police and their partners are actively looking for people whose description has been provided by the Swiss Confederation," the Geneva department of security said in a statement.
Shooting and bomb attacks, claimed by Islamic State, killed 130 people in Paris on November 13. Police in several European countries are still searching for individuals believed to have been involved in the attacks or in their planning.
It was not immediately clear from the Geneva statement, however, whether the suspects were directly linked to the Paris attacks. A Geneva spokeswoman said she had no further comment
UN security guards in Geneva, the European headquarters of the world body, were stationed with MP5 sub-machine guns at entry points for cars, a highly unusual measure at the sprawling complex near the French border.
"It is maximum alert," a second UN guard told Reuters .
Swiss and French officials say they have been working closely together since the Paris attacks.
In an interview days after the attacks, Virginie Perrey, France's security attachee in Switzerland, based in the capital Berne, told French-speaking Swiss TV : "That same evening the (Swiss) federal police called me and two security officers were detached who left for the Swiss embassy in Paris to bring assistance. Obviously information was exchanged immediately."