Spanish police have fired rubber bullets and baton-charged protesters attending a rally against austerity.
The clashes occurred as protesters tried to tear down barriers blocking access to the parliament in Madrid, reports said.
Metal barriers had been placed around the building to block access from every possible direction.
Demonstrators - known as Indignants - say “Occupy Congress” is a protest against the kidnapping of democracy.
Spanish media reported at least 20 people had been arrested and 13 injured in the clashes, as police tried to prevent demonstrators gaining access to Congress.
Thousands of people had massed in Plaza de Neptuno square in central Madrid for the march on parliament.
But their route towards the parliament building’s main entrance is blocked off by metal railings, police vans and hundreds of Spanish riot police.
BBC Europe editor Gavin Hewitttweeted: “In Madrid police firing volleys of rubber bullets at protesters.”
Spain’s provinces have piled pressure on the government with a possible new bailout request and an early election.
Andalucia is considering asking for a 4.9bn euro (£3.9bn; $6.3bn) emergency credit line from the central government, a spokeswoman for the regional administration confirmed to Reuters news agency.
Three other regions - Catalonia, Valencia and Murcia - have already said they will seek emergency funds.
In Catalonia, President Artur Mas called an early election for 25 November, which correspondents say will be a de facto referendum on his demands for greater independence for the province.