WARSAW (AFP) - Hundreds of people in Warsaw on Saturday (May 29) rallied in support of the Belarusian opposition, days after the regime in Minsk diverted a European passenger plane and arrested a dissident journalist onboard.

Among those present were the Poland-based parents of the detained journalist, 26-year-old Roman Protasevich.

"I'm calling on all EU countries and the US to please help us free Roman and (his girlfriend) Sofia, as well as everyone else imprisoned," his mother Natalia Protasevich said.

"We want to live in a free country, in a country where everyone has the right to express his beliefs," his father Dmitry added.

The crowd chanted "Long live Belarus" and held up the opposition's red and white flag as well as signs with slogans such as "Help Belarus," "Freedom for Belarus" and "North Korea in the Middle of Europe".

Protasevich and Sofia Sapega, 23, were arrested on Sunday after Belarus scrambled a military jet to divert the Ryanair plane they were travelling on.

Protasevich's parents said their son looked like he had been beaten in a video later released by Belarusian authorities.

The forced landing triggered a global outcry. The EU has banned Belarusian airlines, urged EU airlines not to cross Belarusian airspace and threatened tough economic sanctions on President Alexander Lukashenko's Kremlin-backed regime.

"Things look really bad now. That's why we need to do something, show those fighting back home that they're not alone," said Natallia Burak, a 35-year-old Belarusian living in Warsaw.

"I have a lot of hope now that Europe will help us, because it's hard to fight against a regime that has everything, that has power, whereas here we are just armed with flags," the saleswoman told AFP.

"As a Belarusian, we see a lot of wild and outrageous things. You know, that same week there was a person killed in prison," said another Warsaw rally attendee, 38-year-old software engineer Alexey.

On Wednesday, Lukashenko said he had "acted lawfully to protect our people" from an alleged bomb threat on the plane.

Often dubbed "Europe's last dictator", Lukashenko has retained his nearly three-decade-long grip on power by hounding opponents, jailing and allegedly torturing dissidents, and muzzling independent media.

He and his allies are already under a series of Western sanctions over a crackdown on protests after his disputed re-election last August.

His opponents say the polls were rigged and that political novice Svetlana Tikhanovskaya, who ran in place of her jailed husband, was the true winner.

Tikhanovskaya, who has been living in exile in Lithuania, tweeted on Saturday that "my husband... was imprisoned by the regime exactly one year ago."

The opposition leader and several hundred others marched to the Belarusian embassy in Lithuania on Saturday to protest Lukashenko's rule, while passing cars honked in support.

"We will win. We will come back home and bring back our loved ones," Tikhanovskaya told the crowd in the capital Vilnius.

"It is our duty to build a new Belarus."