Violence has erupted on the streets of Hong Kong as police attempt to break up a week-long pro-democracy protest.

Hong Kong Police fired tear gas at tens of thousands of demonstrators who want to prevent Beijing from vetting candidates in the next General Election.

Order has broken down in the city with a week of student protests fueled by China's refusal to grant full democracy to the former British colony.

Reporter Mark Stone is with the protesters blocking one of Hong Kong's main roads.

He says it's expected the police will move in ahead of the morning rush hour.