Hong Kong's Chief Executive says pro-democracy protesters must be cleared from the streets of the city by Monday morning.

Leung Chun-Ying’s call comes hours after tens of thousands of gathered in Hong Kong's central business district, calling for his resignation.

Protesters clashed with police today - who used pepper spray and teargas in an effort to disperse the crowds.

It is understood Chinese leaders are concerned the Hong Kong demonstrations will gain traction in other Chinese cities.

Pro-democracy activists want the right to directly choose candidates for an elected office - instead of having China choose the candidates.