A Yemeni security official says unknown gunmen have killed a foreign military expert and wounded his colleague in a drive-by shooting in the capital.

Colonel Mohammed al-Mawri of the Interior Ministry information department said two gunmen on a motorcycle shot the two Tuesday as they left their hotel in Sanaa's Benoun street.

He said the two are military experts working for Yemen's Defense Ministry. An investigation is under way and the ministry is also trying to determine the nationality of the two victims.

Yemen is fighting a war against al-Qaida's local branch, which Washington considers one of the world's most dangerous offshoots of the terror network.

The branch, also known as Al-Qaida in the Arabian Peninsula, regularly strikes security and military targets with drive-by shootings, suicide bombings and other attacks.