BRUSSELS, Dec 18 (Reuters) - Belgian police fired tear gas and water cannon on Thursday as a demonstration by farmers against an EU-Mercosur free trade agreement turned violent, with some protesters hurling rocks and potatoes at police and smashing windows.
Police intervened when the violence escalated and sought to arrest some of the protesters. At one point, a tractor was driven into a line of riot police, although it did not appear to have hit anyone. Some also targeted journalists.
Brussels police said they had authorised a protest with up to 50 tractors, but by early Thursday afternoon around 1,000, mostly with Belgian number plates, had arrived in the Belgian capital. They estimated the number of protesters at 7,000.
EU leaders are set to debate at a summit in Brussels on Thursday whether the EU should sign the deal with the bloc of Argentina, Brazil, Paraguay and Uruguay.
Critics of the trade pact, which has been 25 years in the making, say cheap commodities could flood the market to the detriment of European producers.
(Reporting by Philip Blenkinsop and Charlotte Van Campenhout; editing by Barbara Lewis)
