An official at Japan's embassy in Yemen said a Japanese engineer kidnapped by tribesmen has not yet been freed.
The embassy official spoke Thursday on condition of anonymity because he wasn't authorized to speak to media.
The engineer was kidnapped Sunday just north of the Yemeni capital and tribal mediators said two days later that he was released.
The abductors have demanded the release from prison of a fellow tribesman.
The identity of the engineer has been withheld by the Japanese Embassy.
Tribesmen have frequently kidnapped foreigners to wrest concessions from the government, but they usually treat their captives well and eventually release them unharmed.