China has evacuated more than 3,000 of its nationals from Vietnam following deadly anti-Chinese violence, state media said Sunday, as Vietnamese authorities clamped down to prevent any further unrest threatening vital foreign investment.

Xinhua news agency said the evacuees included 16 Chinese who were "critically injured" last week in unrest triggered by Beijing's deployment of an oil rig in contested South China Sea waters that has triggered rage in Vietnam.

The recent chaos, centred on foreign-owned enterprises, marked the worst anti-China unrest in Vietnam in decades and has stained the developing country's reputation as a stable, welcoming destination for foreign investment.

China said it was dispatching five ships to Vietnam to bring even more nationals to safety as Vietnamese activists sought to stage further demonstrations on Sunday against Chinese "aggression".

The attempted protests were thwarted, however, by a security crackdown that saw hundreds of uniformed and plainclothes security personnel restricting access to streets leading to the Chinese embassy in Hanoi and other suspected protest sites in the capital.

Blogs linked to activist groups said several protest bids in various other cities were thwarted by police who detained a number of activists. The government had earlier ordered authorities nationwide to ramp up security to nip any Sunday demonstrations in the bud.

China's positioning of the oil rig in waters claimed by both sides has inflamed long-simmering enmity between the two quarrelsome communist neighbours, who have fought territorial skirmishes in the past.

Worker demonstrations spread to 22 of Vietnam's 63 provinces in the last week, according to the Vietnamese government, with enraged mobs torching foreign-owned factories and enterprises believed to be linked to China or which employed Chinese personnel.

Hundreds of enterprises were hit, Vietnam's government has said.

The government has in the past occasionally allowed protesters to vent anger at the country's giant neighbour for domestic political gain.

- Vietnam in damage control -

But Vietnam depends heavily on foreign investment for development, and the anti-China violence Tuesday and Wednesday has sent the government scrambling to limit the damage.

"We will not allow any acts targeting foreign investors, businesses or individuals, to ensure that the regrettable incidents will not be repeated," Dang Minh Khoi, assistant to Vietnam's foreign minister, told reporters in a briefing Saturday.

"We ask countries to continue to encourage their investors and citizens to rest assured on doing business in Vietnam."

Officials told the briefing that the violence had left two Chinese nationals dead and 140 injured. More than 300 suspected perpetrators were being prosecuted, they said.

Vietnam attracted $21.6 billion in foreign direct investment in 2013, up from $16.3 billion the year earlier, according to government figures.

The events could have a potential long-term impact on the country's image as a safe place for business, said Edmund Malesky, an expert on Vietnam's investment-fuelled development at Duke University.

"The riots have called that safety into question. In the future, foreign investors will have to balance Vietnam's advantageous labour costs and quality against this potential instability," he said.

More than 3,000 Chinese nationals had been evacuated as of Saturday afternoon, Xinhua reported early Sunday.

- 'Explosion of violence' -

China's foreign ministry also advised its nationals against travelling to Vietnam for now following what it called the "explosion of violence" and urged Chinese citizens to increase safety precautions.

Xinhua said Chinese security chief Guo Shengkun had spoken to his Vietnamese counterpart, urging steps to quell the violence.

There was no immediate response from the Vietnamese government on the Chinese evacuations or travel warning, but officials in recent days have stressed the safety of foreign nationals would be guaranteed.

China's deployment of the giant rig in early May is viewed in Vietnam as a provocative assertion of Beijing's hotly disputed claims to virtually all of the South China Sea, and has been criticised by Washington as exacerbating territorial tensions.

Chinese and Vietnamese vessels have engaged in repeated skirmishes near the rig, including collisions and the use of water cannon.

The violence in Vietnam has further inflamed the situation, with China blaming Hanoi for the unrest. Beijing has refused Vietnam's demands to remove the rig.

Enterprises targeted in the violence included Chinese, Taiwanese, Korean and Singaporean businesses.

It was not clear why non-Chinese businesses were hit, but there is growing resentment in Vietnam over a perceived rise in Chinese workers taking jobs from locals.

Taiwanese President Ma Ying-jeou has ordered commercial jets to be on standby to evacuate its nationals should further violence erupt.

Taiwan-based China Airlines and EVA Airways have already provided extra chartered flights to Vietnam.

The oil-rig confrontation is the latest to spark alarm among China's Southeast Asian neighbours, who have watched as Beijing's increasing insistence on its historic maritime territorial claims over the years has corresponded with a rapid build-up of the Chinese military.

Vietnam groups call for more anti-China protests
Vietnamese civil society groups have called for renewed demonstrations against China in several cities Sunday after Beijing's deployment of an oil rig in contested South China Sea waters triggered the worst anti-China unrest in decades.

But Vietnamese authorities -- who have occasionally allowed demonstrations to vent anger at the country's giant neighbour -- warned they would "resolutely" prevent any further outbursts.

China's positioning of an oil rig in waters also claimed by Vietnam has ignited long-simmering enmity between two communist neighbours who have fought territorial skirmishes in past decades, with protests erupting in major cities in recent days and enraged mobs torching foreign-established factories.

An alliance of 20 vocal Vietnamese NGOs called for fresh protests in the capital Hanoi, the southern economic hub of Ho Chi Minh City, and other areas against China's "aggressive actions" in the South China Sea.

However, it urged participants to remain peaceful following the chaos Tuesday and Wednesday.

"Those violent actions created a bad image for patriotic demonstrations and the people of Vietnam; therefore, they must be stopped," said a statement issued on social media late Friday.

The alliance comprises largely anti-government organisations and is believed to have played a role in stirring the recent protests.

In a text message sent by the government to Vietnamese mobile phone users Saturday, Prime Minister Nguyen Tan Dung said authorities across the country had been ordered to "implement measures to resolutely prevent illegal demonstrations that could cause social and security disorder."

China's deployment of the giant rig is viewed in Hanoi as a provocative assertion of Beijing's hotly disputed claims in the South China Sea and has been criticised by Washington as exacerbating territorial tensions.

There have been repeated skirmishes near the controversial rig in recent days between Chinese and Vietnamese vessels, including collisions and the use of water cannon.

The violent attacks on Chinese personnel at foreign-invested factories in Vietnam have further aggravated the situation, with China accusing Vietnam's government of a role in the unrest.

Beijing, which has refused to budge on the oil rig, has said two Chinese were killed and more than 100 injured over the past week.

China's Xinhua news agency said a delegation led by Assistant Foreign Minister Liu Jianchao met Friday with Vietnamese officials in Hanoi to discuss the rioting.

The report said Liu complained about the unrest and "urged the Vietnamese side to take actions to deal with the aftermath of the riots".

China paper backs 'non-peaceful' steps against Vietnam
Beijing (AFP) May 16, 2014 - A state-run Chinese newspaper backed the use of "non-peaceful" measures against Vietnam and the Philippines Friday, as it considered the possibility of war in the strategically vital South China Sea.

Vietnam is experiencing its worst anti-China unrest in decades following Beijing's deployment of an oil rig to disputed waters, with at least one Chinese worker killed and more than 100 injured.

"The South China Sea disputes should be settled in a peaceful manner, but that doesn't mean China can't resort to non-peaceful measures in the face of provocation from Vietnam and the Philippines," the Global Times newspaper, which often takes a nationalistic tone, wrote in an editorial.

"Many people believe that a forced war would convince some countries of China's sincerely peaceful intentions," the paper added.

Beijing claims almost the whole of the South China Sea, including areas close to the coasts of other littoral states, and the Philippines has provoked its fury by seeking United Nations arbitration in the dispute between the two.