South Sudanese rebels said on Thursday they had freed three oil workers from Pakistan and India that their fighters had seized earlier this month.
The three were released on the orders of the rebels' leader, former vice president Riek Machar, his SPLA-IO group said.
The Pakistani national worked for DAR, a consortium including China National Petroleum Corporation (CNPC), China's Sinopec and Malaysia's Petronas, in Upper Nile state.
The two Indians working for South Sudan's petroleum ministry were kidnapped in north-east Maiwut county.
The three men were flown to Khartoum via Addis Ababa after their release, a Sudanese foreign ministry official told reporters at Khartoum airport when the oil workers arrived.
He said Sudan and Ethiopia had contacted the rebels, at the request of India and Pakistan, to secure the freedom of their nationals.
One of the released men said his rebel captors had told him to pass a message to foreign oil companies to stop operating in South Sudan because oil revenues were being used to fund war.
SPLA-IO deputy spokesman Lam Paul Gabriel said there were no orders given in relation to locals who were seized alongside the foreigners and they would continue to be held.
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 millions 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.