Dozens of Hong Kong police charged pro-democracy protesters with pepper spray late on Sunday afternoon as they struggled to gain control of a key government enclave in the Asian financial hub.

The charge pushed the demonstrators back, but they did not flee.

The protesters were trying to break a police blockade shutting in the core leaders of the Occupy Central protest group, which threatens to shut down Hong Kong's Central financial district to pressure Beijing into allowing full democracy in the former British colony.

The police charge followed red-flagged warnings and lasted for several minutes. Both police and protesters were seen getting medical treatment after the charge but the exact number of injured is unclear.