The Jewish community in Geneva was warned to be ''extremely vigilant’’ as the city went on high alert after police search four men with suspected links to the Isis (Daesh) terror group.

“Sensitive sites have been alerted,” said a government official.

According to daily La Tribune de Genève sources, a Belgian registered utility vehicle entered Switzerland on Tuesday night with two men aboard. Then it was spotted in Geneva before leaving Switzerland. This information was concerning enough to issue a warning to Geneva’s Jewish community.

Officials said the United Nations’ European headquarters is also on maximum alert following intelligence warnings from federal police in the capital city of Berne about people with “possible links to terror.”

The level of alert was immediately raised in Geneva. “The number of patrols has been increased as we are in a highly active phase of search. The threat is now specific” he adds.

The American intelligence service transmitted information on the four individuals sought by the Swiss authorities. The names of four men appear in a note that Tribune de Genève was able to see. In addition the three cities of Geneva, Toronto and Chicago are mentioned as being currently threatened.