At least 30 people have been injured after police used tear gas and water cannon to disperse what was believed to be the largest anti-government protest in South Korea's capital in more than seven years, local media reported. On Saturday up to 80,000 people in Seoul called for the resignation of President Park Geun-hye in demonstrations fuelled by growing frustration over the government's labour policies and rising youth unemployment. Al Jazeera's Harry Fawcett, reporting from Seoul, said the protest shows the "general polarisation" of politics in South Korea. However, he said, the heavy rain on Saturday may have dampened the turn out of the protest. The marches, organised by labour, civic and farmers' groups, brought together protesters with a diverse set of grievances against the government of conservative President Park Geun-hye, including her business-friendly labour policies and a decision to require middle and high schools to use only state-issued history textbooks in classes starting in 2017. Demonstrators, many of them masked, carried banners and chanted "Park Geun-hye, step down" and "No to layoffs" as they occupied a major downtown street and clashed with police, who created tight perimeters with their buses to block them. Protesters tried to move some of the buses by pulling ropes they tied near the vehicle's wheels, and police, wearing helmets and body armour, responded by spraying tear gas at them. Nearby, police sprayed water cannons from above a portable wall to disperse marchers who were trying to advance. There were no immediate reports of injuries. Textbook controversy Earlier in the day, members of the Korean Confederation of Trade Unions, an umbrella labor union, clashed with police who unsuccessfully tried to detain KCTU President Han Sang-goon during a news conference. A Seoul court had issued an arrest warrant for Han over a failed court appearance, after he was indicted for his involvement in organising a May protest that turned violent. Police said the crowd at Saturday's protest was probably the largest at a demonstration in Seoul since May 2008, when people poured onto the streets to protest the government's decision to resume US beef imports amid lingering mad cow fears. Labour groups have been denouncing government attempts to change labour laws to allow larger freedom for companies in laying off workers, which policymakers say would be critical in improving a bleak job market for young people. Critics say that the state-issued history textbooks, which have not been written yet, would be politically driven and might attempt to whitewash the brutal dictatorships that preceded South Korea's bloody transition towards democracy in the 1980s. Park is the daughter of slain military dictator Park Chung-hee, who ruled South Korea in the 1960s and '70s, and whose legacy as a successful economic strategist is marred by records of severe oppression.