South Sudanese rebels said on Monday they had kidnapped four oil workers, including a Pakistani national, in a bid to force a Chinese and Malaysian consortium to leave the country.
The fighters loyal to former vice president Riek Machar said they had seized the four working for DAR Petroleum Operating Company from Upper Nile State on Saturday - the second group of oil workers abducted this month.
There was no immediate comment from DAR, a consortium including China National Petroleum Corporation (CNPC), China's Sinopec and Malaysia's Petronas.
South Sudan, which split away from Sudan in 2011 after decades of conflict, has been mired in civil war since President Salva Kiir sacked Machar in 2013.
The fighting has forced 3 million people to flee their homes, split much of the population along ethnic lines and paralysed agriculture, leaving the country facing famine, according to the United Nations.
South Sudan's government said it was using "diplomatic channels" to negotiate the workers' release and accused the rebels of demanding a ransom.
Rebel spokesman Lam Paul Gabriel dismissed that allegation.
"There are no conditions for their release, but we want to make it clear to their country of residence and the government that we do not want their company to operate in South Sudan," he told Reuters.
He did not say why the rebels wanted the consortium to leave the area bordering Sudan and Ethiopia.
The kidnapping came just over two weeks after two Indian employees of South Sudan's petroleum ministry were seized in northeast Maiwut county.
Last week, the International Organisation for Migration said gunmen attacked an aid convoy in the centre of the country, killing two people and wounding three.