Yemeni security officials say that an unidentified gunman shot and killed a police director in the southwest city of Taiz, the latest in a series of assassinations of the country's security officers.

A gunman on motorcycle shot Police Director Abd el-Wali el-Turkmi in the head while he was driving his car Sunday, the sources say.

The officials spoke on the condition of anonymity because they were not authorized to speak to journalists.

Militants have carried out similar assassinations of military and government leaders in recent years. On Monday, security sources said an intelligence general was shot dead in the province of Lahij, and Iran's economic attache in Sanaa, Ali Asghar Asadi, was killed in a drive-by shooting in Sanaa. Al-Qaida is largely suspected to be behind many of the killings.