Spanish police have fired rubber bullets at demonstrators taking part in a massive anti-capitalism protest march in Barcelona after the European Union summit.
Some demonstrators had set fires in the streets after the march by around quarter of a million people and one appeared to fire a flare at a government building.
Baton-wielding police moved in to disperse the crowds, lashing out with sticks and boots. Some fired rubber bullets.
A sea of demonstrators from a wide range of different groups had marched through city streets to reject the free-market agenda approved by the EU leaders in the city hours earlier.
The march began good humouredly but turned sour after darkness fell, leaving a trail of damage in its wake.
One Reuterscorrespondent in Barcelona's historic old town saw smashed plate glass windows at branches of two banks on the route of the march.
"Eat the rich" had been daubed in red paint in Spanish on one of the bank windows.
Officers at the scene, gazing at office chairs and smashed computer monitors strewn on the pavement outside, said protesters had caused the damage but it was not clear whether anyone had been detained.
Witnesses reported other clashes between police and protesters.
Municipal police estimated some 250,000 people took part in the protest. Organisers estimated that as many as half a million people had joined the march and said they believed it was the biggest demonstration in Barcelona's often turbulent history.
Some 8,500 police officers had been drafted in to the Catalan capital for the summit amid fears of a repetition of protests against globalisation that culminated in the death of a young protester at the hands of Italian police at Genoa last July.
Anti-globalisation activists from across Europe had descended on Barcelona for today's march, held under the title Against the Europe of Capital, to reject the liberal, free-market economic agenda espoused by Europe's leaders.
Some 1,200 protesters from Belgium and France who had hoped to go to Barcelona were barred at the Franco-Spanish border.
Several small demonstrations in Barcelona yesterday ended in clashes with police and 29 people were arrested for disorder and damaging property. Police struck out with batons on two occasions to break up crowds of demonstrators.
Organisers said they had expected the march to be peaceful and said they had commitments from the most hardline groups not to cause trouble.