Protesters cover their faces to conceal their identity as they retreat away from riot police during the demonstration.

China's Hong Kong military garrison warned protesters on Sunday they could be arrested for targeting its barracks in the city with laser lights.

In the first direct interaction between the People's Liberation Army (PLA) and protesters, the PLA raised a yellow flag with the arrest warning written in large letters, said a Reuters witness.

As a few hundred protesters shone laser lights on the barrack walls, troops in fatigues on the roof of the building shone spotlights at protesters and used binoculars and cameras to monitor protesters.