RIOTERS in Hong Kong fired burning arrows at police officers patrolling a university today as schools remained closed over safety fears.

Institutions were shut for the fourth day as groups of mainly student protesters blocked key roads with brick and bamboo barricades and shut down bus services.

The rioters have upgraded their arsenal from makeshift catapults and Molotov cocktails to javelins and bows and arrows.

Marine police evacuated dozens of mainland Chinese students from the Chinese University of Hong Kong by boat on Wednesday.

The campus remains barricaded by protesters preparing for more actions.

Mainland students have posted online about being targeted by protesters breaking into their dormitories and spray-painting abuse.

The Hong Kong Education Bureau said all schools in the semi-autonomous Chinese territory would suspend classes from tomorrow until Sunday due to transport disruption, urging students to stay away from violence.

Hospitals have had to defer non-emergency operations and the government has urged employers to be flexible with workers trapped in the gridlock.

The Chinese government condemned the United States and Britain for provoking the protesters by issuing statements of support.