80 people were injured and 70 arrested in Barcelona and Salamanca last night following clashes between revellers and police.
Mass street drinking sessions fuelled clashes between youths and riot police in the early hours of this morning.
Tens of thousands of young people had gathered in cities around Spain in an attempt to hold the biggest street drinking session or 'botellon' (big bottle).
In the southern city of Granada, police said 25,000 people joined the botellon.
The attempt to create a record botellon was spurred by emails and text messages, in a manner similar to the 'flash mobs' recently fashionable in the US.
The most serious violence was in Barcelona, Spain's second city, where 68 people, including 37 police, were injured and 54 rioters arrested.
There, police used baton charges and fired rubber bullets to try to control the youths, who had been throwing bottles and cans.
Firemen were called out to 50 blazes as the drinkers set fire to rubbish containers in the streets. Shop windows were broken and several shops ransacked.
The Barcelona event degenerated into pitched battles between police and drinkers in the narrow old streets of the city centre that lasted most of the night.
Police blamed the disturbances on about 200 people who they said were out to cause trouble.
