Sudanese officials say local tribal leaders put pressure on the kidnappers to release the workers. They stress no ransom was paid. This is while earlier reports had suggested that the kidnappers had made a $2m ransom demand in return for their safe release.

In a joint statement released through the GOAL charity, the women described their ordeal as a 'difficult time' and said that they were 'naturally thrilled to be released after such a long period in captivity'. They also thanked all those who had worked to secure their release.

Darfur has seen a wave of kidnappings in the past year and aid workers there have had to step up security. Two employees of the UN peacekeeping force in the region are still being held captive.