The Swiss city of Geneva raised its alert level on Thursday and said it was looking for suspects who national officials said had possible links to terrorism.

A security guard at the United Nations' European headquarters said Swiss authorities were searching for four men believed to be in the city or nearby. Another guard said the UN compound was on maximum alert.

Initially, the Geneva department of security said the measures were "in the framework of investigations carried out following the Paris attacks", in which 130 people were killed by Islamist militants a month ago.

But later, federal police in the capital Berne said the statement had been unfortunately worded, and that they had told the Geneva police about people with possible links to terrorism but were not connecting them to the Paris attacks.

Switzerland's Le Matin newspaper said a car registered in Belgium, home to some of the Paris attackers, had driven through a police check near Geneva, prompting police to examine a photograph of four suspected Islamist militants provided by the U.S. Central Intelligence Agency.

The Tribune de Geneve newspaper said a suspect car with two men in it had been spotted in Geneva, which sits on the French border, and then leaving Switzerland. Swiss television said the city's Jewish community had been told to be vigilant.

A Geneva security department spokeswoman said she had no further comment.

The guards stationed at vehicle entry points to the UN grounds were, unusually, carrying Mp5 sub-machine guns on Thursday. One guard said the UN premises had been evacuated for a time late on Wednesday night "as a precaution".

The sprawling complex sits at the heart of "international Geneva". The headquarters of the World Health Organization, the UN human rights office, the refugee agency UNHCR, the World Trade Organization and the International Committee of the Red Cross are a short walk away.

Senior US and Russian diplomats are set to hold talks on Syria in Geneva on Friday.

Swiss and French officials say they have been working closely together since the Paris attacks.

The Swiss Attorney General's office is currently conducting 33 criminal proceedings linked to Islamist militancy, and opened nearly a dozen new investigations in October and November, a spokeswoman said.-Reuters