Geneva security officials said on Thursday that they raised the alert level in the city as they were searching for suspects as part of the Europe-wide investigation into the Paris attacks on Nov. 13, which killed 130 people.
Swiss authorities are searching for four people thought to be in Geneva, which is close to the French border, the United Nations security guards said, adding that the UN compound was on maximum alert.
A statement from the Canton of Geneva's security department said it had received information on Wednesday from Swiss federal authorities concerning "suspicious individuals likely to be in Geneva or the Geneva area."
"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.
UN security guards in the city, the European headquarters of the world body, were stationed with MP5 sub-machine guns at entrances for cars, a rare measure at the sprawling complex near the French border.
"It is maximum alert," one of the UN guard said.
In the statement, it was not immediately clear whether the suspects were directly connected with the Paris attacks.
A Geneva spokeswoman said that she would not make further comment.
After the Paris attacks claimed by DAESH terrorist group that killed 130 people on Nov. 13, police are still hunting suspects across Europe believed to have been involved in the attacks or in their organisation.
Swiss and French officials said that they have been cooperating and working closely since the Paris attacks.
"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," French security attachee in Switzerland Virginie Perrey said.
Investigations were carried out in an attempt to "locate and arrest these individuals", the statement said.
No additional information was provided, but the statement said that more police were deployed across the city.
"Geneva police... have increased their level of vigilance," the statement said.