French riot police fired tear gas at rampaging street protestors Thursday as EU leaders opened a milestone enlargement summit here by signing a Charter of Fundamental Rights for EU citizens. It was a tepid opening, with the charter opposed by some EU members themselves as judicially restrictive, and by street protestors as patronizing and scornful of the disadvantaged. The street clashes, according to police sources, left some 20 policemen injured. A bank was set on fire but quickly doused. Traffic in the centre of this French Riviera playground was snarled. And chic boutiques battened their shutters against breakage and looting. The overriding task of the three-day summit - which could run to four - is to nail down decision-making reforms essential to avoid gridlock and paralysis as the EU expands eastward to as many as 28 countries in a decade. In enlargement reform, the EU leaders are facing their most difficult summit in years: re-writing rules, set down 44 years ago for six founding countries, to accommodate 28. The sticking point is that the 15, having accepted the idea of an historic expansion into the former Soviet bloc and the Mediterranean, are now going to have to relinquish some of their national sovereignty in EU voting to make it work, AFP reports.