A Chinese worker has been killed and almost 150 other people injured as protesters attacked a steel mill in Vietnam, amid anti-China tensions over the South China Sea dispute.
The incident took place at a Taiwanese-owned mill in Ha Tinh province.
It came a day after protesters burnt several foreign-owned factories at an industrial park.
The demonstrations have been sparked by China's movement of a drilling rig into waters also claimed by Vietnam.
Several anti-China protests have since taken place in Vietnam. Nationalist sentiment is currently running very high over the issue, correspondents say.
Protesters appear to have targeted businesses with Chinese characters in their signs, even if they are from places such as Taiwan.
On Tuesday, at least 15 foreign-owned factories were set on fire at industrial parks in Binh Duong province, and hundreds more attacked. No casualties were reported.
The Chinese embassy in Vietnam on Thursday urged Chinese nationals to take precautions in In its second statement in two days.
A Chinese foreign ministry spokeswoman said the violence had "a direct link with the Vietnamese side's indulgence and connivance in recent days with some domestic anti-China forces and lawbreakers".
In an emergency letter to the police ministry, Prime Minister Nguyen Tan Dung called the protests against the "illegal oil rig" a "legitimate action". But he said those who broke the law should be punished and foreign business activities protected.
Taiwanese media said people speaking in Chinese were being targeted.
Ohter reports said some people were trying to leave the country. More than 600 Chinese people had crossed into Cambodia at one border checkpoint alone, Cambodian officials said.
The BBC's Cindy Sui says that Taiwanese airlines are flying bigger planes into Vietnam's airports, and there has been at least one chartered flight to Vietnam to bring back Taiwanese nationals.
The latest incident happened overnight at a huge steel plant owned by Formosa Plastics Group.
One Chinese worker was killed and 149 people hurt, according to Taiwan's envoy in Vietnam and the Ha Tinh government.
- 1954-1975: Communist China backs North Vietnam during the Vietnam war
- 1974: China and South Vietnam fight a bloody war over the Paracel Islands; China seizes Vietnam-controlled islands.
- 1975: Vietnam war ends, Vietnam-China relations deteriorate over Hanoi's ties with Russia and Beijing's support for the Khmer Rouge
- 1979: China and Vietnam fight a border war; thousands of troops die
- 1988: Two sides fight over the Spratly Islands; about 60 Vietnamese sailors killed
- 1991: Sino-Vietnamese ties normalised; trade expands
- 2011: Tensions mount with China over South China Sea exploration; US-Vietnam rapprochement gathers pace
In a statement quoted by Reuters news agency, the company said its Vietnamese and Taiwanese workers were not attacked.
Taiwan's envoy told AFP news agency that rioters forced Chinese workers into a corner of the factory. "The rioters have gone but we are all still concerned they might come back," he said.
The BBC's Nga Pham says the protests have confirmed the government's worst fear that nationalism could easily get out of hand, posing a risk not only to the business environment but also to domestic political stability.
China's Haiyang Shiyou 981 oil rig was brought into waters west of the disputed Paracel Islands earlier this month, leading to collisions between Vietnamese and Chinese ships as Vietnam sought to block the move.
China claims a U-shaped swathe of the South China Sea, including several areas that its South East Asian neighbours say belong to them.
In recent years it has started to enforce these claims more assertively, leading to severely strained ties with the Philippines and Vietnam in particular.