Austria says it is beefing up security measures in Vienna and other cities following warnings of possible terrorist attacks during the holiday season.
"In the days before Christmas, a warning was sent out by a friendly (intelligence) service to numerous European capitals, saying that it could come to an attack involving explosives or a shooting between Christmas and the New Year in crowded spaces," said the Austrian police force in a statement released on Saturday.
The statement added that the names of several probable attackers were referred to in the warning but investigations into these entities had so far yielded no tangible results.
The extra security measures are to include surveillance of crowded areas, "especially at events and traffic hubs" and strict identity checks along with extra scrutiny on objects which may hold explosive devices such as bags and “bicycle frames."
The statement stressed that no public events would be canceled because of the warning.
European nations have been on a high state of alert since a series of attacks in Paris claimed the lives of some 130 people on November 13.