DUBLIN, Ireland (AP) - The head of an Irish humanitarian aid agency appealed Saturday for the release of two of its employees kidnapped in Darfur.

John O'Shea, chief executive of GOAL, said the group had not heard from the abductors of Irishwoman Sharon Commins, 32, and her Ugandan colleague, Hilda Kuwuki, 42. The international peacekeeping mission in the troubled desert region said they were abducted by gunmen in the Kutum area of north Darfur on Friday.

"We have had no contact with the kidnappers and we are very concerned for their safety," O'Shea said.

"We have no indication as to who did this or why and I would appeal directly to the kidnappers to immediately release both these women who are valued colleagues of ours."

A Sudanese government official said Saturday the kidnappers had not been identified.

Mohamed Osman Kebir, the governor of North Darfur, said a search started half an hour after the kidnapping.

"Our security forces followed the traces for about 50 miles (80 kms), but because the dark fell, we lost the trace. But today we are in full contact with all possible sources," Kebir told The Associated Press.

Ireland's Department of Foreign Affairs said the country's ambassador to Egypt, Gerry Corr, was traveling to Sudan "as a matter of urgency" to seek the release of the two women. Ireland does not have an embassy in Sudan.

It is the third kidnapping of foreign humanitarian workers since March.