China has lodged a formal protest with Sudan over the capture of 29 Chinese workers by rebels and dispatched a team to the African nation to help secure their release.

Vice Foreign Minister Xie Hangsheng summoned Sudan's Charge d'Affaires in Beijing Tuesday and filed a complaint over local rebels' attack on a Chinese company camp in Sudan's South Kordofan state Saturday.

China's official news agency Xinhua quoted Xie as telling Sudan's Omer Eisa Ahmed to ensure a safe release of the captives. He also said that his government attaches great importance to protecting Chinese nationals overseas.

Xie also urged Khartoum to take measures to ensure the safety of other Chinese personnel and enterprises in Sudan.

Xinhua also reports that a Chinese team arrived in Sudan's capital Tuesday to help rescue the 29 workers still held by rebels. The report says a spokesman for the rebel group Sudan People's Liberation Army told Xinhua on the phone from Nairobi in Kenya that the 29 have been transported to a safe area and are in good health.

Reports from Sudan say that 18 Chinese workers fled to safety after the attack and headed toward Khartoum.

“We knew the Chinese embassy was trying to rescue us, so we were not scared. Our mind was on how we could cooperate with the embassy and the Sudanese army on their rescue operation. We've called our families and told them we are safe.”

But one of those who fled was still missing Tuesday.

The kidnappings have caused a glitch in Sudan's relations with its powerful ally. China is the largest buyer of oil from Sudan.

South Kordofan borders newly independent South Sudan, which broke away in July. Fighting broke out last year between Sudan and rebels in South Kordofan and in another border state – Blue Nile.