HONG KONG - Hong Kong's acting Chief Executive Matthew Cheung Kin-chung vowed to continue dialogue with the community in remarks following a flag-raising ceremony in the city's center.

The central government "has been strongly supportive to the Hong Kong chief executive and the SAR to govern effectively," Cheung said, referring to the special administrative region. "Hong Kong has been successfully following one country, two systems."

He also warned about the economic fallout from the protests, saying "trade relationships have turned complicated in recent months and are getting severe."

Riot police guarded an early morning flag-raising ceremony at the Hong Kong Convention and Exhibition Centre in the center of the city amid worries that protesters would try and disrupt the event.

With protests anticipated on Tuesday, the city's sole subway operator, MTR Corp. announced additional station closures as a "prudent measure to ensure the safety of passengers and our staff."

The operator said Causeway Bay, Sham Shui Po, Wong Tai Sin, Sha Tin, Che Kung Temple, Tsuen Wan West and Tuen Mun stations would be closed from 11 am. The transit company had earlier said that central, Admiralty and Wan Chai stations, as well as Kowloon’s Prince Edward station, would remain closed.