According to the reporters, many European cities had been alerted by an unnamed friendly intelligence service of possible terror attacks, as per to a statement released on Saturday by police in Vienna, Austria.
As reported, the attacks might take place sometime between Christmas and New Year`s Eve and may involve explosives or guns, according to a statement which did not name the cities that had been warned.
Names of many possible attackers had been included in the warning, the Vienna police have investigated without finding concrete further results.
The security alert had been heightened by the Vienna and other police in Europe, in response to the terror threat warning. The police had increased the police observations and surveillance at public venues, especially at key events and high traffic areas.
It was denied by the French National Police to comment on the warnings when contacted by CNN. They said that not less than 48,000 police officers had been dedicated to security at sensitive sites at the time of school holidays from December 19 to 4th January. It had also been planned by France to recruit 2,000 new police officers next month.