Iraqi intelligence officials say that the shadowy leader of a powerful al-Qaida group fighting in Syria has sought to kidnap United Nations workers.

The officials say they obtained the information about the Nusra Front's leader, Abu Mohammad al-Golani, after capturing members of another al-Qaida group.

They said the men gave them the first known photograph of al-Golani and letters written by the militant leader.

The officials spoke Wednesday on condition of anonymity because they weren't authorized to speak to journalists.

They gave The Associated Press al-Golani's photo and letter excerpts. It wasn't immediately clear when the letters were written.

One U.N. worker was kidnapped for eight months in Syria and was released in October. Another two dozen U.N. peacekeepers were briefly held this year.