China has passed a controversial security law giving it new powers over Hong Kong, deepening fears for the city’s freedom.

It is set to criminalize secession, subversion and collusion with foreign forces, but will also effectively curtail protests and freedom of speech.

The move follows increasing unrest and a widening pro-democracy movement.

Pro-democracy organization Demosisto reacted to the news by announcing it was ceasing all operations.

But some other veteran activists said they would join a key march on Wednesday, despite the risk of arrest under the new law.

Hong Kong was handed back to China from British control in 1997, but under a special agreement that guaranteed certain rights for 50 years.

UK Foreign Secretary Dominic Raab expressed deep concern at the reports that the law had been passed, saying this would be a grave step.

The law had sparked demonstrations in Hong Kong since it was announced by Beijing in May.

China says it was needed to tackle unrest, instability and rejects criticism as interference in its affairs.