HANOI, May 15 -- Vietnamese Prime Minister Nguyen Tan Dung on Thursday ordered the Ministry of Public Security to ensure security and absolute safety for lives and assets as well as normal production of all companies, especially foreign investment firms.

According to the directive on Vietnamese government's website, the Prime Minister urges unanimous, active and firm measures to be implemented to prevent illegal activities and strictly handle those who have provoked riot.

The directive asked local people not to follow illegal actions, in order to ensure security and solidarity and contribute to economic development.

Dung asked relevant agencies to immediately support companies to return to normal production activities, and keep diplomatic missions and foreign investors well-informed of Vietnam's consistent policy.

Vietnam is striving to create favorable conditions and ensure absolute safety for people, enterprises and international organizations in Vietnam in accordance with Vietnamese laws and international commitments of the country, said the directive.

China on May 9 urged Vietnam to respect China's sovereignty and jurisdiction over the Xisha Islands in the South China Sea and stop provocative actions.

Foreign Ministry Spokeswoman Hua Chunying reiterated that the Xisha Islands are the inherent territory of China and there are no disputes in this area. The waters of China's oil drilling operations are only 17 nautical miles from China's Xisha Islands and about 150 nautical miles from Vietnam, she said.

The operations of Chinese companies in waters off the Xisha Islands fall completely within China's sovereignty, she said, noting that it is untenable for any country to make irresponsible remarks or impede China's normal oil drilling in its territorial waters.

From May 3 to 7, Vietnam dispatched 36 vessels, which rammed Chinese vessels for 171 times.

However, Vietnamese Foreign Ministry on May 7 said that Vietnam "cannot accept China's illegal drilling rig HD-981" and "it is an infringement of Vietnam's sovereignty".

With distorted information published by Vietnam's state-run media, the largest ever anti-China demonstrations in the last ten years have been held throughout Vietnam since May 9, and the bloody attacks on Chinese nationals and companies have spread from southern Vietnam on Tuesday to central and northern Vietnam on Thursday.