* Anti-WTO protesters rampage in central Geneva
* Protesters say multinationals manipulate WTO
* Switzerland bars three South Korean protesters
(Adds end of demonstration, updates numbers, adds arrests)
By Laura MacInnis
GENEVA, Nov 28 (Reuters) - Anti-capitalism protesters smashed the windows of banks, shops and cafes in central Geneva and set cars on fire during a demonstration on Saturday against the World Trade Organisation.
Organisers including unions and Switzerland's Green Party broke off the march, called to protest against the a three-day WTO conference starting on Monday, after masked protesters in the main crowd rampaged through the centre of the city.
Protesters set fire to four cars near the city bus station, causing a thick cloud of smoke. Police used tear gas to disperse the violent protestors and no further damage was caused, a police statement said.
Police blocked off access to the WTO's lakeside headquarters, which the marchers had planned to pass.
The police blamed the violence on some 200 masked demonstrators, known as the "black bloc", out of a total crowd of 3,000. Police arrested 17 people and seized fireworks, iron bars, bicycle chains, sprays, spanners and other objects.
VIOLENT FRINGE, GOOD-NATURED CROWD
The violent protesters were a minority in the otherwise peaceful crowd which was accompanied by a dozen tractors and a marching band.
Protesters held up signs saying "Stop Capitalism, No WTO", "WTO is enemy of the climate" and "We will not sell our souls to the multinationals".
Before the violence erupted, Vera Weghmann, a 24-year-old student from Germany, said corporations play an unseen lobbying role at the WTO, steering its agreements in their favour.
"We see the WTO making policies for the big companies, not for the people," she said, wearing a wedding gown with the label "WTO" and walking arm in arm with Ole Hoffmann, 23, whose suit bore the corporate logos of Deutsche Bank, Barclays and Standard Chartered.
Two other "WTO brides" walked beside "grooms" with suits carrying the logos of food and drugs multinationals like Kraft, Coca-Cola, Nestle, Roche, Pfizer, Novartis and Bayer.
Activists say trade policies adopted by WTO members create poverty in rich and poor countries by squeezing farmers in developing countries and depressing labour standards in industrialised nations.
Police spokesman Patrick Pulh told Reuters three South Korean activists wanting to take part in the demonstration and other protests and workshops during the conference had been refused entry to Switzerland at Geneva airport on instructions from the federal government in Berne.
Yoon Geum Sum, of the Korean Women Peasant Association, one of the groups organising the protests, said the three had been stripped and body-searched.
"This is a violation of human rights and a criminalisation of social movements. Our demand is their immediate release and an apology from the Swiss government," she said in a statement.
The last major demonstration in Geneva was in January during the World Economic Forum conference in Davos, when police fired tear gas and water cannon to disperse demonstrators. (Editing by Jonathan Lynn and Robin Pomeroy) ((jonathan.lynn@reuters.com; +41 22 733 3831; Reuters Messaging: jonathan.lynn.reuters.com@reuters.net ))