British broadcaster Sky has said it has received a security threat amid a widening wave of hoax threats disrupting passenger flights across Europe.

Newsrooms in Ireland and Bulgaria also received emailed bomb threats on Friday from a purported “Mikhail Andropov”, who claimed responsibility for the hoax threats seen across the continent this week.

Irish public broadcaster RTE was forced to evacuate its offices and suspend programming after receiving the threat.

Bulgaria’s Nova TV was also a recipient.

The messages were headlined “Message to the West” and portrayed the threats as the prelude to a series of attacks on means of transport across Europe.

Reuters was not able to establish the identity of the sender, the origin of the emails, or whether they had in fact come from the same source as the threats to any or all ⁠of the dozens of flights affected since Tuesday.

But they added to concern among European officials that the hoaxes are part of a campaign of “hybrid” disruptions, which many have blamed on Russia, aimed at countries that have helped Ukraine.

Moscow has denied involvement.

Spanish Foreign Minister Jose Manuel Albares said Europe appeared to be facing “hybrid aggression ⁠and a form of psychological warfare”.

Security experts stated on Thursday that the threats might be intended to penalise European nations that have supplied arms or funding to Ukraine as it resists the full-scale invasion launched by Russia in 2022.

It remained possible, however, that individuals were creating false trails, issuing copycat threats, or simply acting on personal grievances.

Around half a dozen flights suffered disruption in some way on Tuesday, followed by more than two dozen on Thursday, with several planes making unexpected landings or receiving fighter jet escorts to their destinations.

On Friday, an Italian airport authority source reported that a Wizz Air flight travelling from Prague to Rome had been diverted to Venice. Despite more than a dozen hoax threats, direct disruption to air travel was far lower overall.

Hungarian jets did, however, escort airliners flying from Brussels to Sofia and from Prague to Bucharest and Cyprus while passing through Hungarian airspace. Defence Minister Romulusz Ruszin-Szendi said Nato had ordered air patrols in the region, marking the initial report that the Western defence alliance had become involved.

While no nation attributed blame for the threats, they follow a series of sabotage attacks across Europe, ranging from German electricity substations to defence facilities in the Baltic region, and supermarket refrigerators in France and elsewhere. Germany directly blamed Russia for a drone attack on Leipzig airport.

Many European officials have accused Russia of a campaign of “hybrid” or “grey zone” disruptions that are essentially cheap to execute, easy ‌to deny and not expected to trigger an armed response.

European technology commissioner Henna Virkkunen told Reuters on Thursday that since 2022 Europe had faced a range of hybrid operations including sabotage of critical infrastructure, drone incursions, cyber breaches and election interference. “We are under attack all the time,” she said. “The reason behind ⁠these operations is to destabilise our societies and create mistrust among our citizens.”

“It is not always Russia who is behind different hybrid operations,” she said, before adding: “Quite often it is Russia.”

On Thursday, an airport source in Italy said bomb threats had been sent to several airlines and airport operators in ‌Rome and Milan purporting to be from “fighters ​of the Male State”, a far-right anti-feminist movement banned in Russia.

Reuters ‌could not confirm who had sent the email. Vladislav Pozdnyakov, a ​Russian blogger who set up Male State in 2016, said it no longer existed and was not involved in any way.