Vietnam flooded major cities with police to avert protests against China on Sunday in the wake of rare and 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 attacks on Chinese workers and Chinese-owned businesses last week, and Beijing sent five ships on Sunday 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, as Vietnam's communist rulers stuck to their vow to thwart any repeat of last week's violence in three provinces in the south and center of the country.