JUBA (Reuters) - Six aid workers kidnapped by rebels in South Sudan earlier this week have been released, according to the United Nations and a spokesman for the rebels.

The aid workers are from the French organization Solidarites International and had been kidnapped on Sunday while traveling on a road near the city of Raja, in the west of the country.

“All of them were released and they have landed safely in Wau,” another city in the west of the country, a United Nations official in Juba who spoke on condition of anonymity told Reuters. He said one of those who had been held by the rebels was a foreigner.

Rebel spokesman Lam Paul Gabriel told Reuters that the six humanitarian aid workers had been freed: “All their belongings were given back to them including their vehicles.” It was not clear why the rebels had taken the aid workers and their vehicles into custody.

Solidarites said in a statement on Monday that it had lost contact with three members of its team on Saturday. [L8N1OI50M]

It gave no indication of their fate and it was not immediately clear why it gave a different number of those involved.

The spokesman for Solidarites in Paris did not immediately respond to a request for comment on the announcement of the release of its staff. The army spokesman in Juba also did not respond to request for comment.

South Sudan is one of the world’s most dangerous countries for aid workers. Some 28 aid workers have been killed this year, with nine shot dead in November alone, according to the United Nations.

The world’s youngest nation is embroiled in a civil war that has killed tens of thousands of people and forced a third of the 12 million strong population to flee their homes.