US lawmakers have supported Hong Kong protesters by passing a bill aimed at upholding human rights in the city.

The bill - which still needs to pass the upper house, the Senate - would mandate an annual review, to see whether Hong Kong had sufficient autonomy from the rest of China to justify its special trading status, reports BBC.

The lower chamber also approved stopping tear gas exports to Hong Kong.

On Monday, Hong Kong protesters took to the streets to support the US bill.