HONG KONG- Fresh scuffles erupted between pro-democracy activists occupying central parts of Hong Kong and riot police, as the protests entered their second week.

Thousands of people held a rally overnight, defying the Beijing-backed authorities, although by Sunday morning many of the protesters had gone home.

On Saturday Hong Kong's leader warned that police would ensure government offices and schools reopened on Monday.  Activists oppose China's plans to vet candidates in 2017 elections.

During the overnight rally thousands chanted: "Democracy now! Democracy in Hong Kong!" as speakers from the pro-democracy movement urged them to persist in their campaign. The scuffles occurred in the early hours of Sunday in the Mong Kok district, with police using pepper spray against some of the protesters.

The comment by Hong Kong leader CY Leung came after earlier street fights led to the postponement of talks between the government and the protesters. Leung said he "strongly condemned" the violence but warned that it was likely to continue unless "social order" resumed.

"The government and the police have the responsibility and resolution to take all actions necessary to resume social order," he said.

He added that the "most urgent thing" was for protesters to allow government staff to return to work and to clear main roads so schools can reopen on Monday.