Beijing: China on Monday warned Chinese firms operating in Sudan to beef up security after 29 of its workers were captured by rebels in the African country, forcing Beijing to shift 17 of its nationals from the camp.

China's Commerce Ministry warned all Chinese firms based in Sudan to take precautionary measures. Chinese companies should closely monitor changes in the country's security situation and take stronger precautions to ensure the safety of lives and property, the Ministry said in a statement here.

A group of Sudan People's Liberation Army (SPLA) on Saturday attacked a site of a Chinese company building a road in South Kordofan state.

A spokesman of the SPLA's northern sector said on Saturday that the movement was holding 29 Chinese nationals working at the site.

Meanwhile, a total of 17 Chinese workers have been shifted to a safe place by the Sudanese army after their camp was attacked by rebels, while another 29 Chinese were still held by the abductors, the Chinese Embassy in Sudan said on Monday.

"When the rebels attacked the camp of the Chinese company near Al-Abbasiya town in South Kordofan, there were 47 Chinese workers.    Twenty-nine of them were abducted and 18 fled to neighbouring areas," an official at the Chinese embassy said.

"The Sudanese army found 17 Chinese workers and transported them to a safe area. Efforts are underway in search for the other one worker," he said.

Arno Taloudy, the SPLA spokesman was quoted as saying by Xinhua thatg "armed clashes took place between our forces and the Sudanese army at an area near Al-Abbasiya Tagali town in South Kordofan."

"We have controlled the area and 29 Chinese were held," he said.

"The Chinese workers have been transported to a safe area and they are in good health and in safe hands," he added.

China is Sudan's major trading partner, the largest buyer of Sudanese oil, and a key military supplier to the regime in Khartoum. This is first time that China ran into problems after its aggressive investment push in Africa.

South Kordofan, located on the Sudan-South Sudan border, has witnessed armed clashes between the Sudanese army and the SPLA's northern sector since June 2011.

South Kordofan is one of the three areas hit by conflict since South Sudan became independent from Sudan in July.

Problems started after the recent division of Sudan into North and South.

South has retained the oil resources but is unable to ship them to the outside world as the North headed by long-time Chinese ally Omar al-Bashir demanded high transit fee for using.