About 2,000 Basque separatists clashed with French police in Bayonne yesterday, only a few km from Biarritz, attacking police and summit buses and throwing rocks in running skirmishes with tear gas-firing riot squads.
The protesters, trying to march the 12 km from this medieval city to the Atlantic resort of Biarritz, attacked a police station halfway along the route, injuring three police so badly they had to be taken to hospital, the local prefecture said.
Hooded protesters attacked four buses shuttling delegates and journalists to the summit, roughing up their drivers, and overturned a police car and broke shop windows before retreating, it added.
Police rounded up 20 protesters, most of them Spanish citizens. "Arrangements to expel them rapidly are being made," an official said.
Police also briefly detained some 40 militants who managed to stage a short protest in the centre of the chic summit city, where 3,000 police were called in to keep order, and 19 more who held a short demonstration in another part of Biarritz.
Authorities have banned rallies in Biarritz, where the two-day EU summit is being held, but let hundreds of Spanish Basque activists enter the Basque region of southwestern France on Thursday.
Extra security was laid on for Spanish Prime Minister, Mr Jose Maria Aznar, but the protesters had no hope of nearing the summit delegates meeting at the plush beachside casino at Biarritz.
The protesters are campaigning for the independence of the Basque country and for the release of ETA (Basque Homeland and Freedom) prisoners held in Spain and France.
ETA has killed some 800 people in Spain in its fight for Basque independence, some of them local politicians from Mr Aznar's conservative Popular Party.
Parallel to the Basque protests, a smaller "counter-summit" held debates among leftist groups denouncing globalisation.
About a dozen journalists working for Basque-language media said they had been refused accreditation to the summit, apparently on the orders of the French interior ministry.
"It's incomprehensible. It's the first time we've had this kind of problem," said Mr Hur Gorostiaga of the Basque publication Egunkaria.