Anti-government protests that have roiled Hong Kong for more than three months spread to the sports field on Tuesday, as many local fans defied Chinese law to boo the country's national anthem ahead of a soccer World Cup qualifier against Iran. The latest sign of unrest in the former British colony followed another weekend of sometimes violent clashes, in which police firing tear gas engaged in cat-and-mouse skirmishes with protesters who at times smashed windows and started fires in the streets. Earlier on Tuesday, the city's Beijing-backed leader, Carrie Lam, warned against foreign interference in Hong Kong's affairs, adding that an escalation of violence could not solve social issues in the Asian financial hub. Hong Kong returned to Chinese rule in 1997 under a "one country, two systems" formula that guarantees freedoms not enjoyed on the mainland. But many Hong Kong residents fear Beijing is steadily eroding that autonomy. Weeks of protests over a now withdrawn extradition bill have evolved into a broader backlash against the government and greater calls for democracy. At Hong Kong's main stadium on Tuesday night, a sizeable contingent of the crowd of more than 10,000 football fans jeered and held up "boo" signs as China's anthem played before the game, while others chanted "Revolution of our time" and "Liberate Hong Kong". Disrespecting the national anthem is an offense in China. Other fans sang "Glory to Hong Kong," a song that has become a rallying cry for more democratic freedoms in the semi-autonomous Chinese territory. "We hope we can unite Hong Kong," said one of those booing, Ah Wing, wearing a red Hong Kong team shirt and glasses. "Even if we lose, we'll keep going. That's what we do against strong teams, against strong enemies." Some local fans continued to chant protest slogans during the match, which saw Iran beat Hong Kong 2-0. -Reuters