A leading Taiwanese diplomat in Vietnam said the rioters lit fires at several buildings at a steel mill operated by Taiwan's biggest investor, Formosa Plastics Group, in overnight disturbances that began late on Wednesday.

Ambassador Huang Chih-peng said Taiwanese management was not targeted, but that Chinese workers were, one of whom was killed. Police also confirmed the death of a Chinese national.

However, a local doctor reported that a total of 20 people had died, according to news agency DPA.

The doctor said about a hundred people had been sent to Ha Tinh General Hospital overnight.

Vietnamese police and military units intervened after hundreds of people reportedly broke into the premises, in the Tnh Ha Tnh province.

There were similar scenes across other parts of southern Vietnam on Wednesday. The unrest came amid national anger over the May 1 deployment of a Chinese oil platform to a part of the South China Sea that is also claimed by Vietnam.

Warning to Chinese citizens

Violence had also broken out from Tuesday night into Wednesday, in particular at industrial parks around Ho Chi Min City. As a result, China's Foreign Ministry issued warnings to Chinese citizens in the country and called upon Vietnamese authorities to protect them.

The Vietnamese government said such protests had initially been peaceful, but were hijacked by "extremists." Many of the factories were attacked by mobs who appeared to believe the businesses were Chinese, when they were in fact Taiwanese or South Korean.

Anti-Chinese sentiment has reached fever pitch after a deep-sea oil rig was towed close to the Paracel Islands, which are controlled by China but claimed by Vietnam, on May 1. The move resulted in a clash between Vietnamese boats and Chinese ships sent to protect the rig.

Beijing and Hanoi had maintained close relations until the most recent trouble, successfully keeping a lid on the tensions over disputed maritime areas, which also include the Spratly Islands. China has maritime disputes with several of its neighbors around the South China Sea, including Taiwan, Brunei, Vietnam, Malaysia and the Philippines.

rc/kms (AFP, AP, Reuters)