BRUSSELS — Western outrage grew and the European Union threatened more sanctions Monday over the forced diversion of a plane to Belarus in order to arrest an opposition journalist in a dramatic gambit that some said amounted to state terrorism or sheer piracy.

Ryanair said Belarusian flight controllers told the crew there was a bomb threat against the plane as it was crossing through the country’s airspace and ordered it to land in the capital of Minsk. A Belarusian MiG-29 fighter jet was scrambled to escort the plane — in a brazen show of force by President Alexander Lukashenko, who has ruled with an iron fist for over a quarter-century.

The goal was seemingly to arrest Raman Pratasevich, a 26-year-old activist, journalist and prominent critic who ran a popular messaging app that played a key role in helping organize massive protests against the authoritarian leader. He and his Russian girlfriend were led off the plane shortly after landing — and authorities haven’t said where they’re being held. The plane, which began its journey in Athens, Greece, was eventually allowed to continue on to Vilnius, Lithuania.

World Leaders Condemn the Plane Diversion and Arrest

U.S. Secretary of State Antony Blinken called the diversion “shocking” and appealed for Pratasevich’s release. EU leaders were particularly forceful in their condemnation of the arrest and move against the plane, which was flying between two of the bloc’s member nations and was being operated by an airline based in Ireland, also a member.

The bloc summoned Belarus’ ambassador “to condemn the inadmissible step of the Belarusian authorities” and said in a statement the arrest was yet again “another blatant attempt to silence all opposition voices in the country.”

Czech Prime Minister Andrej Babis said that “the scandalous incident in Belarus shows signs of state terrorism and it’s unbelievable.” Irish Prime Minister Micheal Martin told broadcaster RTE that the episode “reflects growing authoritarianism across the world.”

EU Commission President Ursula von der Leyen earlier said it amounted to a “hijacking.”

EU Leaders Threaten More Sanctions Against Belarus

EU leaders have tried to bring Belarus closer to the bloc — to encourage democratic reforms and reduce the influence of Russia — but they have failed so far. On Monday, hours ahead of a previously planned summit, some EU leaders were threatening more sanctions — from scrapping landing rights in the bloc for Belarus’ national airline to exclusions from sporting events.

Without waiting for the EU’s decision, Latvia’s airBaltic said it would avoid using Belarusian airspace, and Lithuania’s government said it would instruct all flights to and from the Baltic country to the country as well starting Tuesday.

British Transport Secretary Grant Shapps also said he has instructed the U.K. Civil Aviation Authority “to request airlines avoid Belarusian airspace in order to keep passengers safe.” He added that he was suspending the permit allowing the Belarusian flag carrier Belavia to operate in the U.K.

The U.S. and the EU already have imposed sanctions on top Belarusian officials amid months of protests, which were triggered by Lukashenko’s reelection to a sixth presidential term in an August vote that the opposition rejected as rigged. More than 34,000 people have been arrested in Belarus since then, and thousands were brutally beaten.

The Belarusian Foreign Ministry on Monday bristled at what it described as “belligerent” EU statements, insisting that the country’s authorities acted “in full conformity with international rules.”

‘Case of State-Sponsored Hijacking’

Amid the tensions, Lufthansa said that a flight from Minsk to Frankfurt with 51 people on board was delayed Monday following a “security warning.” It was eventually allowed to depart with all passengers on board after the authorities searched the plane, put the passengers through another security check and unloaded all luggage and freight.

On Sunday, flight tracker sites indicated the Ryanair plane was about 10 kilometers (six miles) from the Lithuanian border when it was diverted. There have been conflicting reports of what exactly happened.

Lukashenko’s press service said the president himself ordered a fighter jet to accompany the plane after he was informed of the bomb threat. Deputy air force commander Andrei Gurtsevich told Belarusian state TV that the plane’s crew made the decision to land in Minsk, adding that the fighter jet was sent to “provide help to the civilian aircraft to ensure a safe landing.”

But Ryanair said in a statement that Belarusian air traffic control instructed the plane to divert to the capital. The plane was searched, and no bomb was found.

Ryanair’s CEO Michael O’Leary described the move as “a case of state-sponsored hijacking … state-sponsored piracy.”

In an apparent reference to the Belarusian security agency that still goes under its Soviet-era name KGB, O’Leary he told the Irish radio station Newstalk that he believes “some KGB agents offloaded from the aircraft” in Minsk.

Pratasevich and Girlfriend Taken into Custody by Belarusian Authorities

Of the 126 people aboard the flight initially, only 121 made it to Vilnius, according to Rolandas Kiskis, chief of criminal police bureau in the Lithuanian capital where a pre-trial investigation investigation has begun.

Passengers described Pratasevich’s shock when he realized that the plane was going to land in Minsk.

“I saw this Belarusian guy with girlfriend sitting right behind us. He freaked out when the pilot said the plane is diverted to Minsk. He said there’s death penalty awaiting him there,” passenger Marius Rutkauskas said after the plane finally arrived in Vilnius. “We sat for an hour after the landing. Then they started releasing passengers and took those two. We did not see them again.”

Pratasevich’s girlfriend, Sofia Sapega, is a student at a university in Vilnius.

Pratasevich was a co-founder of the Telegram messaging app’s Nexta channel, which played a prominent role in helping organize major protests against Lukashenko.

Nearly 2 million Belarusians in the nation of 9.3-million people have followed the channel, which has served as the main conduit for organizing demonstrations and offered advice on how to dodge police cordons. It also has run photos, video and other materials documenting the brutal police crackdown on the protests.

The Belarusian authorities have labeled the channel “extremist” and leveled charges against Pratasevich of inciting mass riots and fanning social hatred. He could face 15 years in prison if convicted.

In November, the Belarusian KGB also put Pratasevich on the list of people suspected of involvement in terrorism, an ominous sign that he could face even graver accusations. Terrorism is punishable by death in Belarus, the only country in Europe that maintains capital punishment.

Amid the international outrage, Moscow quickly offered a helping hand to its ally.

Russian Foreign Minister Sergey Lavrov said the episode needs to be investigated — but that it couldn’t be rushed. The two neighbors have close political, economic and military ties, and Lukashenko has relied on Moscow’s support amid Western sanctions.