China finalised a sweeping overhaul of Hong Kong's electoral system on Tuesday, drastically curbing democratic representation in the city as authorities seek to ensure "patriots" rule the global financial hub.

The measures are part of Beijing's efforts to consolidate its increasingly authoritarian grip over its freest city following the imposition of a national security law in June, which critics see as a tool to crush dissent.

The changes would see the number of directly elected representatives fall and the number of Beijing-approved officials rise in an expanded legislature, Xinhua news agency reported...