Yemen's security directorate in Aden says a suicide bomber attacked the security chief's motorcade in the southern port city, killing five of his bodyguards.

In a statement, it says Shallal Shayei was unharmed in Sunday's attack, as was Aden governor Aidroos al-Zubaidi, who was travelling with him. A similar attack on the two was foiled on Monday, and on Thursday a suicide car bomber in women's clothes detonated explosives near Shayei's home, the third attack on his house since December.

Soldiers deployed to the area after the car bombing, which sent a cloud of black smoke rising into the air.

Yemen has been mired in a conflict pitting Shiite Houthi rebels against the internationally-backed government, which is allied with a Saudi-led coalition. Extremists have gained ground amid the chaos.