BEIJING, May 26 -- China on Monday urged Vietnam to severely punish those who perpetrated violence against foreigners in riots earlier this month.

"We have noticed that two people were sentenced in Vietnam," Chinese Foreign Ministry spokesman Qin Gang said at a daily news briefing after a Vietnamese worker was sentenced to three years in prison and another to one year for their roles in the riots.

Protests broke out about two weeks ago in some Vietnamese cities and escalated into looting and violence targeting Chinese enterprises and nationals following Vietnam's disruptions to China Oilfield Services Limited's normal drilling in waters off China's Xisha Islands in the South China Sea.

The violence left at least two Chinese dead and more than 100 others injured.

"We do not think the punishment is enough," said the spokesman, urging the Vietnamese side to conduct a thorough investigation into the riots as soon as possible, severely punish the criminals in accordance with law, compensate the losses of the people and companies affected, and take concrete and effective measures to ensure the safety of Chinese enterprises and citizens in Vietnam.

"Only in this way will the international community resume confidence in (Vietnam)," he added.