A Pakistani petroleum engineer, who had been kidnapped from his workplace in South Sudan, was released on Thursday, confirmed family members and government officials.

An employee of DAR Petroleum Operating Company, Ayaz Hussain Jamali was among the four oil workers who were abducted from South Sudan's capital city of Juba earlier in March.

Fighters loyal to former vice president Riek Machar had kidnapped the engineers in a bid to force DAR, a Chinese and Malaysian consortium, to leave the country.

Jamali's sister Abida told Dawn that their other brother, Babar, who also works in the same company in South Sudan, informed the family in Sindh's Badin district that the 28-year-old engineer has been recovered.

Abida thanked the Pakistani and Chinese government, the International Committee of the Red Cross (ICRC) as well as the media in helping to ensure her brother's safe recovery.

Foreign ministry spokesperson Nafees Zakaria confirmed the news, saying that the Pakistani missions in Khartoum and Addis Ababa had been working with the governments of all countries involved to secure Ayaz's release.

"We are grateful to the governments of Sudan, South Sudan and China for their cooperation and support to ensure the successful release of Mr Ayaz Jamali," Zakaria said.

According to a statement issued by the ministry, the foreign office also engaged the ICRC in Islamabad and Juba, South Sudan, in its efforts to secure Mr. Jamali’s release.

"A team of ICRC officials, based in Juba was the first to establish contact with the rebels, visit Jamali in captivity and confirm his safety," the statement added.

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 three 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 had accused the rebels of demanding a ransom. However, rebel spokesman Lam Paul Gabriel had 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," Gabriel had said.