Police in Belgium are preparing for rioting to spread into the country after more than 400 people were arrested in the Netherlands during days of violent protests against a Covid-19 curfew.
Hundreds of posts have been shared on social media platform Telegram urging people in Belgium to join the protest.
Violence erupted after the Dutch government imposed an evening curfew in an attempt to curb the spread of infection, a move that led to three nights of rioting.
It broke out on Saturday with the torching of a coronavirus testing centre in the Dutch fishing village of Urk.
Police used water cannon and tear gas to break up crowds throwing fireworks and petrol bombs and to stop looting in other parts of the country, including Amsterdam. On Tuesday, police again arrested dozens of people.
Now, Belgian interior minister Annelies Verlinden has issued warnings over the threat of the riots spreading.
Calls for protests against Belgium's tough lockdown and overnight curfew have mounted on social media following the Dutch disorder.
“The violent demonstrations that degenerated in the Netherlands have apparently incited certain people to call, also in our country, for demonstrations against the health measures,” Ms Verlinden said.
Belgium, where the 27-nation EU headquarters is situated, has had one of Europe's worst Covid-19 outbreaks proportionally, with the nation of 11 million people recording more than 20,800 confirmed virus-related deaths to date.
The wearing of protective masks in public places is compulsory. A night-time curfew and shopping restrictions are in place, and a ban on all non-essential travel was introduced on Wednesday until March at the earliest, limiting movement ahead of next month's school holidays.
There is clamour online for a protest on Sunday at major Brussels landmark the Atomium.
In a letter to regional mayors, Ms Verlinden said that any demonstrations held without permission must be prevented.
The letter said that authorised protests could not involve more than 100 people, must respect rules on social-distancing and mask-wearing, and must be contained in one place and not involve a march.
She reassured officials that they can count on police reinforcements if needed.
Ms Verlinden told broadcaster RTBF on Wednesday that she was hopeful violent riots would not break out in Belgium. “But it’s better to be proactive. We’ve read the messages on social media networks, we have to avoid that happening here,” she said.
For days, social media platforms have been awash with encouragement for people to demonstrate in Turnhout, Sint-Niklaas and Maasmechelen on Saturday.
"My phone has been ringing off the hook since Monday," Turnhout mayor Paul Van Miert told newspaper De Standaard.
"A lot of people have already seen the call. Even though it is often a screenshot of a screenshot, it is an ink blot that is expanding.
Our police force is trying to find out who is responsible for this call, but it is not easy. We take this very seriously because we are close to the Dutch border."
Police in Maasmechelen launched an investigation and enlisted cyber security experts to find those responsible for the incitement.
"The call for the possible uprising next Saturday has been posted on social media," spokesman for the Lanaken-Maasmechelen police Johnie Nijs said.
"We have started an investigation. We regularly receive screenshots of concerned citizens."
Mr Van Miert urged people to maintain peace.
"We had no significant incidents during the entire corona period and we will keep it that way. The local police are ready, both on the spot and online," he said.
"According to our indications, it is more about local people who try to sabotage things via social media, people with bad intentions stirring up the community.
"Our police chief knows what to do if necessary. The most important thing is to keep the peace and to vaccinate."
In the Netherlands, several cities granted police extra powers to deal with the disturbances.
"You don't capitulate to people who smash shop windows," the country's Finance Minister, Wopke Hoekstra, said. "Scum does this."
Police unions called it the worst rioting in four decades and Dutch police chief Henk van Essen condemned the violence. "It has nothing to do any longer with the right to demonstrate."
Justice Minister Ferd Grapperhaus said the curfew would remain in place. It is expected to last until February 9 at the earliest, in what the government says is a vital step to bring down the number of Covid-19 cases.
More than 13,600 people have died in the Netherlands since the start of the pandemic.
