A huge explosion has killed the governor of Yemen's southern Aden province and six of his bodyguards in an attack claimed by a local Islamic State affiliate.

Governor Gaafar Mohamed Saad was travelling to his office when the explosion struck his convoy in the southern port city.

Authorities are investigating the exact cause of the explosion.

An IS affiliate claimed the attack in a statement circulated online by supporters, saying the bomb was concealed in a parked car along the convoy's route.

The group referred to Mr Saad as a "tyrant" and warned the "heads of the infidels" in Yemen that it would carry out "operations to chop off their rotten heads".

IS has claimed a series of bombings that killed 159 people and wounded 345 this year in Yemen.

The extremists have been able to expand their reach in the chaos of Yemen's larger conflict, between a loose array of pro-government forces backed by a Saudi-led coalition and Shiite Houthi rebels, who control the capital, Sanaa, and large parts of northern Yemen.

Pro-government forces drove the Houthis out of Aden earlier this year.

A local al-Qaida affiliate has exploited the chaos to seize territory in Yemen's south and east, and has a growing presence in Aden.

On Saturday, masked gunmen in Aden killed a military intelligence official and a judge known for sentencing al-Qaida militants. No one claimed those attacks.