Belarus is guilty of a “war-like act” for forcing a Ryanair flight carrying an opposition activist and journalist to land in Minsk, the chairman of the Commons foreign affairs committee has said.

The opposition in Belarus and western officials have denounced the incident on Sunday, which led to the arrest of Raman Pratasevich, as a hijacking operation by the country’s government.

Pratasevich is a prominent opponent of Belarus’ authoritarian president Alexander Lukashenko and could face 15 years in jail if convicted of several charges.

He was on board the Ryanair flight from Athens, Greece, to the Lithuanian capital of Vilnius when it changed course to head for the Belarusian capital.

Tom Tugendhat, the Conservative committee chairman, said the move showed the Belarus regime was now a “state sponsor of terror”.

“If it’s not an act of war, it’s certainly a war-like act,” he told BBC Radio 4′s Today programme. “We simply cannot tolerate that.”

Tugendhat said all flights in, out and over Belarus should be stopped to protect the safety of passengers.

Anne-Marie Trevelyan, the energy minister, said the UK government was “profoundly alarmed” by what appeared to be an “outlandish action” by Lukashenko.

Dominic Raab, the foreign secretary, is due to make a statement later on Monday.

Flight tracker sites indicated the plane was about six miles from the Lithuanian border when it was diverted. 

Ryanair said in a statement that Belarusian air traffic control had instructed the plane to divert to the capital.

Lithuanian president Gitanas Nauseda called the incident a “state-sponsored terror act”.

He said that the European Council would discuss the case on Monday and that he would propose banning Belarusian planes from European Union airports and levelling “serious sanctions” against Lukashenko’s government.

Lithuania’s foreign minister, Gabrielius Landsbergis, said: “Belarusian airspace is completely unsafe for any commercial flight, and it should be deemed this not only by the EU but by the international community. Because now, this instrument could be used for any plane crossing Belarusian airspace.”

Pratasevich is a co-founder of the Telegram messaging app’s Nexta channel, which officials in Belarus last year declared as extremist after it was used to help organise major protests against Mr Lukashenko.

The protests have dwindled in recent months, but Belarus authorities are continuing to crack down on the opposition with arrests.

Passengers were taken off the plane in Minsk. After the plane arrived in Vilnius, defence minister Arvydas Anusauskas said Pratasevich’s girlfriend and four other people did not reboard.

“We will find out who are the other four that did not travel with the rest. Lithuania has launched an investigation to find out what really happened on that plane,” he said on Facebook.

Exiled opposition leader Sviatlana Tsikhanouskaya has called on the International Civil Aviation Organisation (ICAO) to begin an investigation.

“It is absolutely obvious that this is an operation by the special services to hijack an aircraft in order to detain activist and blogger Raman Pratasevich,” she said in a statement.

“Not a single person who flies over Belarus can be sure of his safety.”

European Commission president Ursula von der Leyen tweeted: “It is utterly unacceptable to force @Ryanair flight from Athens to Vilnius to land in Minsk.”

German foreign minister Heiko Maas said “such an act cannot be left without definite consequences from the side of the European Union” and called for Mr Pratasevich to be released.

US secretary of state Antony Blinken called the incident “shocking” and accused Mr Lukashenka’s government of endangering the lives of those aboard the aircraft, some of them Americans.

“Independent media are an essential pillar supporting the rule of law and a vital component of a democratic society. The United States once again condemns the Lukashenka regime’s ongoing harassment and arbitrary detention of journalists,” he said.

Months of protests erupted in Belarus after last August’s presidential election, in which Lukashenko won a sixth term in office.

Police cracked down on the demonstrations, detaining around 30,000 people and beating many of them.

Although protests died down during the winter, Belarus has continued to take actions against the opposition and independent news media.

Last week, 11 staff members of the TUT.by news website were detained by police.