China urged Sudan?in Beijing?on Tuesday to take substantial and effective measures to ensure the safety of Chinese personnel after four Chinese workers were kidnapped and killed.

"It is one of the most serious killing cases of oversea Chinese workers in recent years and we are very shocked by it," Chinese Foreign Minister Yang Jiechi said via a phone conversation with his Sudanese counterpart Deng Alor.

"The Chinese side feels strong indignation and condemns the inhumane terrorist act by the kidnappers on unarmed Chinese company staff, " Yang told Alor, according to a press release from the Chinese Foreign Ministry on Tuesday evening.

Sudanese officials earlier reported to the Chinese Embassy in Sudan that five of the nine kidnapped workers were killed on Monday, with two rescued and two missing. It revised the numbers late Tuesday afternoon, saying four were killed, four were rescued and the other was still missing, according to the Foreign Ministry.

The nine workers from the China National Petroleum Corporation (CNPC) were kidnapped from an oil field near the western Sudanese region of Darfur on October 18.

The Chinese Embassy said they were taken by unknown militants in the Southern Kordofan State, but no armed group had claimed responsibility for the kidnapping.

"The Chinese leaders and Chinese government are highly concerned about the case, asking for the utmost rescue efforts with the precondition of ensuring the safety of the kidnapped," Yang, who is among the entourage of Chinese Premier Wen Jiabao 's visit to Russia, added.

"We hope the Sudanese side will continue its rescue effort, bring the murderers to severe punishment, and take all substantial and effective measures to prevent similar things happening again," Yang said.

Alor expressed his condolences to the victims and his sympathy to the victims' families as well as the Chinese government and Chinese people, promising that the Sudanese government would continue its rescue mission for the missing Chinese worker, make the utmost efforts to bring the murderers to justice and protect the safety of Chinese people in Sudan, according to the statement.

(Xinhua News Agency October 29, 2008)