One Frenchman was killed and another injured in an attack on a car in Sanaa the capital of Yemen.
European Union foreign policy chief Catherine Ashton has condemned the killing of the dead man who was working for the EU delegation, “in the strongest terms”.
The words were echoed by French president Francois Hollande. He said every effort would be made to catch the gunmen.
So far no group has claimed responsibility after a four-by-four vehicle without registration plates blocked the car.
“We heard the shooting and we ran to the scene where we found two Frenchmen wounded by unknown gunmen – we don’t know who is behind the attack,” said an eyewitness.
Monday’s killing comes after a German diplomat was wounded last month during what was believed to be an attempted kidnapping.
Yemen is home to al Qaeda in the Arabian Peninsula, which authorities have blamed for a string of attacks on security forces.
The Yemeni army last week launched a major offensive in several militants strongholds.