The Hong Kong government has reminded residents who are already in the United States or intend to visit the country to pay attention to personal safety in view of the ongoing protests and riots there.

"The government reminds residents who intend to visit the United Stated or are already there to monitor the local situation, exercise caution, attend to personal safety, avoid large gatherings of people, and pay attention to local announcements on the latest situation," a spokesman said.

The Security Bureau will continue to closely monitor the situation there.

Meanwhile, the Chinese consulate in Los Angeles told the country's citizens in the area to strengthen personal security amid unrest in America's second-biggest city.

"Chinese citizens in the region [should] strengthen personal security measures, stay away from gatherings, crowded areas, or places with poor public security, and avoid going out at night or travelling alone," the consulate said in a statement.

They should also closely monitor official announcements and raise their safety awareness, it added.

The warning came as Los Angeles police ordered the public to disperse from the downtown area after further unrest, with cars torched and security forces firing tear gas at protesters, in the wake of US President Donald Trump's deployment of National Guard troops to the city. (Additional reporting by AFP)