South Korean police clashed violently with protesters opposing US beef imports in Seoul on Sunday, leaving more than 100 people injured, officials and witnesses said.
Police fired water cannon and wielded batons to try to control protesters, who hit back with poles and steel pipes, smashing police bus windows and spraying street fire hoses.
With rocks also hurled through the air, many of the injured suffered head wounds and were taken to hospitals in ambulances, according to witnesses on the scene.
A Seoul police spokesman said more than 30 troops were injured in the prolonged overnight clashes, while protest organisers claimed more than 100 citizens were hurt.
The violence began late Saturday when police stopped thousands of protesters from marching to the presidential office after holding a rally which had been attended by about 15,000 people.
Seoul's decision to resume the US beef imports has sparked mass demonstrations for weeks against the supposed dangers of mad cow disease and against government policies in general.
After the street protests first erupted, Seoul went back to Washington to secure extra safeguards -- though both governments insist the meat is safe.
Secretary of State Condoleezza Rice, on a visit to Seoul Saturday, urged South Koreans to trust official assurances that US beef is safe.
Despite the extra safeguards, South Korean protests have intensified since Seoul's formal resuming of the imports on Thursday. Unionists threaten to block the release of US beef to the market.
Seoul signed the controversial deal in April to resume the imports, suspended in 2003 after a US mad cow case, in hopes of pushing forward with a wider free trade agreement (FTA).
The FTA was signed last year but must be ratified by the legislatures of both countries.