South Korean police arrested nearly 160 people at an overnight rally in downtown Seoul opposing the resumption of US beef imports, an official said Saturday. About 5,500 people rallied in the capital on Friday, a national holiday in South Korea, and the protest continued until early Saturday, when police fired water cannons to disperse the crowd. Some minor scuffles occurred between police and demonstrators, a police official said on condition of anonymity, citing an office policy. Police arrested 157 people on charges of staging unauthorized demonstrations, illegally occupying streets and defying orders to disperse, the official said. The first shipment of US beef under a controversial import deal arrived in South Korea last month, amid lingering public concerns over mad cow disease.