The Kremlin said Tuesday it regrets Europe's plans to cut air links with ex-Soviet Belarus and avoid its airspace after the diversion of a Ryanair flight carrying an opposition activist.

The aircraft travelling from Athens to Vilnius landed in the Belarus capital Minsk after a supposed bomb threat.

The incident caused a global outcry, with EU-based carriers cutting air links with Belarus and European leaders warning of fresh sanctions.

"We can only express regret. It is very expensive for any company to fly around the territory of a rather large country located in the centre of Europe," Kremlin spokesman Dmitry Peskov told reporters.

"In the end these recommendations will cost the passengers of the planes, who will be in the air for an extra half-hour or hour," he said.

Belarus President Alexander Lukashenko and his allies are already under European and US sanctions for the handling of protests that gripped the country after a disputed presidential vote in August 2020.

Opposition journalist Roman Protasevich, who was aboard the diverted Ryanair flight, was arrested at Minsk airport and authorities say he is being held in a pre-trial detention centre.

His girlfriend Sofia Sapega, a Russian national who was with him on the flight, was also detained.

Peskov said he "hopes that in the near future" she will be released.

"Unfortunately, our citizens are being detained in different parts of the world. We always provide legal assistance," he said.

Protasevich, 26, fled to Europe in 2019 from where he co-ran the Nexta Telegram channels, a key Belarus opposition media that helped mobilise protesters.

In Belarus he faces charges of organising mass unrest, an offence punishable by up to 15 years in jail.