The messages, headlined "Message to the West", portrayed the threats as a prelude to attacks on means of transport across Europe.

The messages, headlined "Message to the West", portrayed the threats as a prelude to attacks on means of transport across Europe.

Officials across Europe report more bomb threats against flights after a series of hoaxes caused diversions this week. Two broadcasters also received security threats. It's unclear who is behind the wave of hoaxes.

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

False bomb threats targeting aircraft across Europe are part of hybrid operations designed to exhaust state resources, spread panic and test security services, cybersecurity expert Lyubomir Tulev and national security and counterterrorism expert Col. Asen Peychev said on NOVA NEWS.

The bomb threats involved two passenger planes bound for Warsaw, a Ryanair flight from London to Spain, two flights to Rome and a flight traveling from Israel to the Bulgarian capital, Sofia. No explosives were found.