Hong Kong: Fierce clashes broke out between protesters and riot police in Hong Kong on Sunday as thousands marched through the strife-torn city, during a day of global protests aimed at casting a shadow over communist China's upcoming 70th birthday.

Beijing is preparing for huge, tightly-choreographed festivities from Tuesday to mark the founding of the People's Republic of China, including a huge military parade that will revel in the country's emergence as a global superpower. But ongoing unrest in Hong Kong threatens to upstage those celebrations as the semi-autonomous city boils with public anger over the erosion of its special freedoms under Beijing's rule.