No confirmation that operation is linked to last month's terror attacks in Paris
Police in Switzerland are hunting for four terror suspects and the national security alert level has been raised, according to reports.
Guards with MP5 sub-machine guns have been stationed at the entry points to the United Nations complex in Geneva as the search continues, Reuters reports.
Despite earlier reports, Swiss federal police said they have no information linking suspects to the deadly attacks in Paris last month in which 130 people were killed.
Swiss federal authorities tipped-off the officers, and the department of security said: "The Geneva police, on the basis of this information, have increased their level of vigilance and reinforced the number of police agents on the ground".
Geneva is more than 250 miles southeast of Paris. Police in Belgium and elsewhere have been searching for Salah Abdeslam, who rented a car which was used to carry gunmen to the Bataclan theatre in Paris, since the attacks.
The Brussels-based suspect - the brother of one of the suicide bombers - is thought to have fled Paris on the night of the massacres.
The third gunman involved in the attack on the music hall has been identified as a 23-year-old man from Strasbourg.
Foued Mohamed Aggad went to Syria with his brother and a group of friends at the end of 2013.
Most of the others were arrested in spring last year when they returned to France, however Aggad stayed in Syria.
The attackers all died at the scene. Two had already been identified as Omar Ismail Mostefai, 29, and 28-year-old Samy Amimour.
Earlier this week members of the US band Eagles Of Death Metal broke down in tears as they returned to the Bataclan theatre for the first time since the attacks.
They laid flowers and read cards at the site, where 90 people were killed when extremists stormed the venue as the band performed last month.