Vietnam flooded major cities with police to avert anti-China protests in the wake of deadly rioting in industrial parks that deepened a tense standoff with Beijing over sovereignty in the South China Sea.
China has evacuated more than 3,000 nationals following the attacks on Chinese workers and Chinese-owned businesses last week.
Beijing sent five ships today to bring more people home, China's state-run Xinhua news agency reported.
Several arrests were made in the capital Hanoi and commercial hub Ho Chi Minh City within minutes of groups trying to start protests, according to witnesses.
Vietnam's communist rulers stuck to their vow to thwart any repeat of last week's violence in three provinces in the south and centre.
Fury has gripped Vietnam after Chinese state energy firm CNOOC deployed dozens of ships two weeks ago and towed a $1billion oil rig to a location 240km off Vietnam's coast in an area both counties claim.
It was one of the most assertive moves China has made in seas believed to be endowed with billions of barrels of oil.
It came just days after US President Barack Obama visited several Asian allies engaged in territorial disputes with China.
US officials in Washington described China's action as provocative, and said Beijing's fraught relations with its neighbours could potentially strain ties with the United States.
State sanctioned protests took place last week.
However, what started as a peaceful march in two southern industrialised provinces on Monday spiralled a day later into a rampage of arson, destruction and looting of Chinese-owned factories, and Taiwanese businesses mistaken for being Chinese.
Fighting between Vietnamese and Chinese workers broke out in central Ha Tinh province on Wednesday killing two people and wounding 140, the government said.
China's foreign ministry also put the casualties at two dead and 100 injured, Xinhua said.
A doctor and an eyewitness, however, said they saw between 13 and 21 dead bodies, mostly Chinese, on the night of the unrest.
Sixteen critically injured Chinese nationals were evacuated from Vietnam early today aboard a chartered medical flight arranged by the Chinese government, the foreign ministry said in a separate statement.
The violence has angered China, which has demanded swift action against the perpetrators and for Vietnam to do more to protect Chinese nationals and businesses.
Police and traffic police gathered in small clusters on street corners in the centres of Hanoi and Ho Chi Minh City today, where large numbers of people were milling around in hot and humid conditions in anticipation of rallies.
Trucks with loudspeakers circled parks and stopped at intersections telling onlookers to disperse.
A handful of people who tried to start a protest in Ho Chi Minh City were rounded up and taken away in a van as sirens blared.