Swiss police have increased the alert level in Geneva after they reportedly received intelligence of four terror suspects believed to be connected to the Paris attacks in the area.

In a highly unusual move, United Nations security guards were seen stationed with MP5 sub-machine guns at entry points for cars at the international facility.

A security guard at the headquarters, which roughly 9,000 staff operate from, told Reuters Swiss authorities were allegedly searching for “four guys” believed to be in the area as part of a Europe-wide investigation followin the attacks on Paris in November.

"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," the Geneva department of security said in a statement to Reuters.

The attacks on the French capital on 13 November killed 130 people and shocked Europe. In the wake of the atrocities, Brussels faced a week-long shut-down as authorities combed parts of the city for individuals believed to have been involved in the attack. One of the suspects - Salah Abdeslam - is believed to still be on the run.

In pictures: Saint-Denis raid Show all 33 1 /33 In pictures: Saint-Denis raid In pictures: Saint-Denis raid A man is arrested by police officers at the site where a raid happened in the city center of Saint-Denis, near Paris In pictures: Saint-Denis raid Hooded police officers detain a man in Saint-Denis, near Paris In pictures: Saint-Denis raid Hooded police officers detain a man in Saint-Denis, near Paris In pictures: Saint-Denis raid Police officers detain a man on the ground inside a shopping mall in Saint-Denis In pictures: Saint-Denis raid Police officers arrest a man in Saint-Denis, a northern suburb of Paris In pictures: Saint-Denis raid French police officers storm a church after a raid in Paris suburb Saint-Denis In pictures: Saint-Denis raid Police officers at work at the site where a raid happened in the city center of Saint-Denis In pictures: Saint-Denis raid Some people are being transferred to a local hospital near the site of this morning police raid in Saint-Denis In pictures: Saint-Denis raid Residents are evacuated in Saint-Denis In pictures: Saint-Denis raid Inhabitants are evacuated from a security perimeter set in the northern Paris suburb of Saint-Denis city center In pictures: Saint-Denis raid Families are evacuated by police members at the site were a police raid happened in the city center of Saint-Denis In pictures: Saint-Denis raid Rescue teams take care of an injured police officer at the site where a police raid happened in the city center of Saint-Denis In pictures: Saint-Denis raid Members of special French RAID forces with a police dog and French riot police (CRS) secure the area during an operation in Saint-Denis In pictures: Saint-Denis raid Police forces operate in Saint-Denis, a northern suburb of Paris In pictures: Saint-Denis raid French riot police (CRS), soldiers, firefighters and health workers stand at the scene in Saint-Denis In pictures: Saint-Denis raid French riot police (CRS) secure the area as shots are exchanged in Saint-Denis Reuters In pictures: Saint-Denis raid Rescue teams and police gather at the site where raid happened in the city center of Saint-Denis In pictures: Saint-Denis raid Soldiers operate in Saint-Denis, a northern suburb of Paris AP In pictures: Saint-Denis raid Police officers take up positions in Saint-Denis, a northern suburb of Paris AP In pictures: Saint-Denis raid Police and Ambulance vans are parked in Saint-Denis, a northern suburb of Paris AP In pictures: Saint-Denis raid A resident is being searched by police officers in Paris suburb Saint-Denis AP In pictures: Saint-Denis raid Members of French police special forces in the northern Paris suburb of Saint-Denis city center, as French Police special forces raid an appartment, hunting those behind the attacks that claimed 129 lives in the French capital In pictures: Saint-Denis raid Anti-terrorist police raid apartment in Saint Denis, Paris. Reports suggest the target of the police siege in Saint-Denis is Abdelhamid Abaaoud, thought to be the mastermind behind the Paris attacks. Three suspected terrorists have barricaded themselves in an apartment gunfire has been exchanged between the men and dozens of armed police Rex In pictures: Saint-Denis raid French special police forces secure the area as shots are exchanged in Saint-Denis Reuters In pictures: Saint-Denis raid French police evacuate residents in Saint-Denis Reuters In pictures: Saint-Denis raid Police officers take up positions in Saint-Denis, a northern suburb of Paris AP In pictures: Saint-Denis raid Police forces prepare in Saint-Denis, a northern suburb of Paris AP In pictures: Saint-Denis raid French spolice stop and search a local resident as shots are exchanged in Saint-Denis In pictures: Saint-Denis raid French police members participate in an raid in the city center of Saint-Denis EPA In pictures: Saint-Denis raid French special police forces secure the area as shots are exchanged in Saint-Denis Reuters In pictures: Saint-Denis raid Firemen wait for the develop of the operation in the city center of Saint-Denis EPA In pictures: Saint-Denis raid French police secure the area as shots are exchanged in Saint-Denis Reuters In pictures: Saint-Denis raid French special police forces secure the area as shots are exchanged in Saint-Denis Reuters