Police in Denmark and the Czech Republic investigated threats to air traffic on Friday, while a Romanian plane received a bomb threat following a string of hoaxes that have targeted flights across Europe this week.

A flight from Prague to Bucharest operated by Romanian carrier Tarom received a bomb threat. The plane landed at its intended destination, and airport administration officials said the bomb threat proved to be false.

In the Danish capital, Copenhagen, police said Friday they were present at the airport for a second consecutive day “in connection with threats directed at air traffic.” They said their immediate assessment was that there had been no danger to passengers or to others at the airport. It added that air traffic was proceeding safely and without disruption.

Czech police also said they were again dealing with threats against planes on Friday. They said necessary security measures have been taken in cooperation with Prague’s Vaclav Havel Airport that have “a minimal impact on the normal operations at the airport.”