Protesters pelt police during clashes at the end of a demonstration by tens of thousands people coming from some 20 European countries in the European district of Brussels to denounce the austerity measures in Europe.

More than 25,000 people took part yesterday in a European trade union demonstration in Brussels against austerity, while more than 20 people were injured in the protest that at times turned violent, a police spokeswoman said.

A “minority” of demonstrators were aggressive, throwing objects including stones and barriers, and “anything they could find”, said police commissioner Ilse Van de Keere.

Eight protesters and three police officers were taken to hospital with injuries, while around 16 people received first-aid treatment for minor wounds, Van de Keere added.

The demonstration passed the US embassy, where some protesters were seen hurling stones and firecrackers towards police.

The embassy was placed under lockdown.

Police officers used water cannon in the area near the embassy – located close to the royal palace – and around the European Union institutions headquartered in Brussels, according to police and witness reports.

Belgian broadcaster RTBF described demonstrators marching among a “forest” of red flags, and throwing bins at the police.

Several demonstrators were masked, according to witnesses.

The demonstration was organised by the European Trade Union Confederation (ETUC) to protest against austerity measures prescribed in response to Europe’s economic crisis.

“Austerity is not working. Austerity is causing a mounting social and economic crisis: over 26mn Europeans are jobless,” ETUC leader Bernadette Segol said ahead of the demonstration, demanding “a new path for Europe, based on investments, quality jobs and equality.”

Anger at EU austerity measures is expected to prompt a voter backlash in European elections on May 22-25, with large gains predicted for extremist and eurosceptic parties.

Union officials said some 40,000 people joined the march.

“Politicians have to consider that this is the key issue for the future. We are asking to stop the austerity and start a big investment programme for sustainable growth and quality jobs,” Segol said.

EU unemployment in February was 10.6% and, for those under 25 years, 22.9%.

In Greece and Spain, the jobless rate is more than a quarter and youth unemployment above 50%.

The Brussels regional government and police had warned drivers to stay clear of the centre yesterday. Public transport was also hit.