Two Chinese passenger ships have arrived at a Vietnamese port to evacuate Chinese workers following deadly rioting last week, a decision that intensifies the dispute between the two countries.

The boats with a capacity to carry 1,000 passengers each arrived at Vung Ang port on Monday morning, but did not immediately dock, said Thai Tran Linh, a Vietnamese government official in Ha Tinh.

He said officials were still examining the paperwork of the ships, which left China's Hainan Island on Sunday, the AP news agency reported.

Vung Ang port is part of a large, under-construction Taiwanese steel mill complex 250km south of the capital Hanoi that was overrun by an anti-China mob last week.

Two Chinese workers were killed and 140 injured in the attack at the facility, which employed about 3,000 Chinese workers.

There has been no violence or protests since last Thursday, and Chinese people have been able to leave the country independently with no impediments since then.

Around 400 other factories around the country were damaged or destroyed in mob violence, most in industrial parks close to southern Ho Chi Minh City.

Many factories were not Chinese-run but were targeted by mistake, or by gangs intent on looting.

Vietnam's government, furious at China's positioning of the rig, initially allowed street protests, but since the rioting the authorities have begun a crackdown.

Tense standoff

The nationwide unrest, the worst to hit Vietnam in years, followed Beijing's deployment of a large oil rig in a patch of the South China Sea also claimed by Vietnam.

Both nations have sent ships to the waters that are now locked in a tense standoff, raising fears of a possible conflict.

Al Jazeera's Adrian Brown, reporting from Beijing, said many analysts believed that China wanted to test US "resolve" in the region. He added that Chinese leaders "want to know just how far America is prepared to go in protecting its allies".

China has territorial disputes with several states in the region, including US ally, Japan.

Both countries claim sovereignty over a group of islands in the East China Sea.