Bangkok: The dangerous stand-off over an oil rig in a disputed area of the South China Sea has pushed Vietnamese authorities to crack down on fierce anti-China protests and forcibly break up small demonstrations in two cities.

Witnesses in southern Ho Chi Minh City said police dragged away several demonstrators from a park in the city centre.

Vietnam’s Prime Minister Nguyen Tan Dung ordered an end to all “illegal protests” amid expectations of more anti-China unrest in Ho Chi Minh City and Hanoi, as Vietnam and China feuded over the placement over a $US1 billion ($1.06 billion) Chinese oil rig in the South China Sea.

China, meanwhile, had evacuated more than 3000 of its nationals via flights and was sending five ships to evacuate more, the state-run Xinhua news service reported on Sunday.