Belgian riot police used tear gas and water cannon to disperse thousands of people protesting in Brussels against a UN migration pact.
Demonstrators held aloft banners bearing slogans including "Our people first" and "We have had enough, close the borders."
The protest outside the European Union headquarters in Brussels was organised by Flemish right-wing parties and had initially been banned, but the ban was overturned at the weekend by Belgium's high court, which cited the right to protest.
A minority of the estimated 5,500 demonstrators became violent when they were asked to disperse and began throwing paving stones, street furniture and firecrackers at security forces near the European Commission building.
Police responded with tear gas and water cannon.
A counter-demonstration of around 1,000 people took place peacefully in the centre of the Belgian capital, organised by left-wing groups and non-governmental organisations in favour of the non-binding UN migration pact.
The right-wing New Flemish Alliance (N-VA), the biggest party in parliament, pulled its ministers from the ruling coalition last week after Belgian Prime Minister Charles Michel refused its demand that he not sign the UN migration compact in Marrakesh.
It was a move that leaves Mr Michel, who belongs to the liberal Mouvement Reformateur party, at the helm of a minority government with five months to go before legislative elections.
The UN pact is aimed at creating a global approach to migration and was initially supported by all four parties in Belgium's coalition.
But the N-VA reversed its position in October and later voted against it, along with the far-right Vlaams Belang party.
Marine Le Pen, leader of France's far-right National Rally, and Steve Bannon, a former adviser to US President Donald Trump, denounced the UN pact at an event in Brussels last weekend.
"The country that signs the pact obviously signs a pact with the devil," Ms Le Pen said.
The UN pact was agreed in July by all 193 UN members except the United States, but only 164 formally signed it at a meeting last Monday in Morocco.
Critics say the deal could increase immigration to Europe.
Ten countries, mostly in formerly communist Eastern Europe, have pulled out of the pact.
With a record 21.3 million refugees globally, the UN began work on the pact after more than one million people arrived in Europe in 2015, many fleeing civil war in Syria and poverty in Africa.
The deal is expected to be ratified at UN headquarters in New York on Wednesday.
