South Sudan announced Wednesday it had expelled the head of Chinese-Malaysian oil consortium Petrodar after finding the company in "secret deals" with Khartoum, in the latest incident troubling Chinese investors in the region.

South Sudan's government on Tuesday expelled Liu Yingcai, the Chinese head of Petrodar on the grounds of "lack of cooperation," Reuters quoted Pagan Amum, the secretary-general of the ruling Sudan People's Liberation Movement, as saying in Juba.

"We are asking the partners to appoint a new president," Amum said, adding that relations with China were good, "but there were difficulties with some oil companies."

Qian, a staff member with China National Petroleum Corp's office in Juba, told the Global Times that the basis for expelling Liu was groundless.

"Juba shifted its conflicts with Khartoum to oil companies," Qian said. Investors at Petrodar are drafting a protest letter to the South Sudanese government, but communications with authorities remain open so as to ease the tension.

CNPC holds 41 percent of the shares at Petrodar while Sinopec has 6 percent. Petrodar has a production capacity of 240,000 barrels a day.

On Sunday, Petrodar, a consortium mainly made of Sinopec, CNPC and Malaysia's Petronas, denied that it had helped Khartoum in seizing Juba's oil exports.

 On January 21, Juba ordered companies to cease all their crude oil productions in the country due to the ongoing spat with Khartoum.

Barnaba Marial Benjamin, South Sudan's information minister, told AFP the decision had been taken after an investigation into millions of barrels of oil that South Sudan claims were stolen by Khartoum.

According to the Sudan Tribune, officials in Juba have threatened to expel Chinese companies operating on its territory if they are proven to be complicit with Khartoum in seizing oil exported from South Sudan.

Juba took three-quarters of Khartoum's oil production capacity when it became independent in July, but still needs to export crude through a northern pipeline and a Red Sea port in Sudan.

The two sides have failed to agree on transit fees Juba needs to pay, prompting Khartoum last month to seize at least three South Sudan oil shipments at the Red Sea terminal.

He Wenping, a deputy director of Western Asian and African Studies at the Chinese Academy of Social Sciences, told the Global Times Wednesday that Petrodar may be a victim of the oil dispute between Juba and Khartoum.

"South Sudan has not provided any convincing evidence supporting the accusation. It may want to put pressure on China to force Khartoum into an oil agreement," she said.

According to the Sudan Tribune, some officials in Khartoum have argued that South Sudan's threats against Chinese companies are part of a wider conspiracy to replace them with Western companies.

China is currently the biggest buyer of Sudanese oil.

The latest incident came shortly after two abduction cases targeting Chinese workers in Northeast Africa rang alarms for Chinese investments in the region.

On January 28, 29 Chinese workers were abducted by the Sudan People's Liberation Movement-North near the border between Sudan and South Sudan. They were released about a week later.

On January 31, 25 Chinese workers were kidnapped in Egypt but were freed within days.

"These are lessons for China in terms of evaluating the risks before investing in those areas. Precautions must be taken to ensure the safety of workers," He Wenping noted.

She warned that some Western politicians have tried to depict Chinese investments in Africa as being a new form of colonialism, stirring anger among locals toward Chinese people, and that Beijing needs to take note of this sentiment and improve its future approaches.

In January 2011, US Secretary of State Hillary Clinton said that China had extended its influence across Africa and displayed traits of "new colonialism" in the continent.

South Sudan's oil minister Stephen Dhieu told the Sudan Tribune Wednesday that the country had already started reviewing contracts which he said were signed between Khartoum and oil companies prior to South Sudan's independence.

On February 3, Sudanese President Omar al-Bashir said the tense atmosphere between Sudan and South Sudan was making war more likely than peace, after South Sudanese President Salva Kiir Mayardit refused to sign a framework agreement on transit fees.

"The oil row leaves a seed of conflict in the region. The negotiation needs the international community's commitment because the lasting dispute threatens the global oil market as a whole," He Wenping said.

Agencies and Qiu Wei contributed to this story