Several flights across Europe have been disrupted by bomb threats for the second time this week.
Around 10 flights have been affected so far today, with some diverted.
On Tuesday, at least seven flights and a cruise ship received bomb threats, causing disruption at airports across Europe, although no devices were discovered.
While no country has attributed blame for the threats, they come at a time when European officials have been blaming both Russia and Iran for what they describe as "hybrid attacks" and acts of sabotage. Moscow and Tehran both deny any such campaign.
This week, unidentified hackers shut down fridges in supermarkets in several European countries. Some experts said hoax bomb threats could be part of a similar pattern of low-cost, deniable disruption efforts.
On Thursday, Bulgarian officials reported three aircraft making emergency landings because of bomb threats. Airplanes flying from Copenhagen and Madrid landed in Sofia, the interior minister said, according to broadcaster bTV. A third aircraft, from London, landed in Plovdiv, local media said.
Four planes heading to Prague received bomb threats and police were preparing for their landing, Czech police said on X, adding they assessed the credibility of the threats as low. "Nevertheless, we are not underestimating the threat, which is why all necessary security measures have been activated with minimal impact on passengers and airport operations," police said. "After landing, all aircraft will undergo pyrotechnic inspections."
Aer Lingus flight EI402 from Dublin to Rome landed safely at Evreux airport, 100 km west of Paris, after being diverted as a security precaution, the Irish airline said in a statement.
Belgian media reported that an airliner forced to land at Brussels' Zaventem airport belonged to the Polish airline LOT.
A Finnair flight from Helsinki, operated by Jettime, landed as normal in Vienna after receiving a bomb threat, a spokesperson for the Finnish carrier said.
Finnair earlier said another Finnair flight, to Rome, had landed after receiving a bomb threat.
Polish airlines LOT said that a flight from Warsaw to Brussels landed safely at its destination after a security warning and no threat was confirmed.
"Following receipt of information regarding a potential security threat to flight LO235 from Warsaw to Brussels, the flight crew was notified of the situation and conducted an onboard inspection in accordance with established procedures. No suspicious items were found," a LOT spokesperson said.
The aircraft landed at Brussels Airport, where security services carried out an additional inspection of the plane, which revealed no dangerous or suspicious items.
