Three stonemasons have died after a section of the historic walls around the Old City of Kairouan in Tunisia collapsed on Saturday.

Officials say a 30m section of the wall near the Gate of the Floggers crashed to the ground.

Two others were also injured in the accident and are said to have suffered fractures

An investigation has been opened into the accident. Authorities say it could be linked to recent heavy rain.

Moez Tria, a spokesperson for the Civil Protection Department said a perimeter had been set up to stop people from walking under part of the wall which is still at risk of further collapse.

The city of Kairouan was founded in 670 AD and is one of North Africa's holiest cities.

It was the capital of the Muslim world in North Africa for four centuries, before Tunis was chosen as Tunisia's political capital in the 12th century.

Kairouan became a Unesco World Heritage site in 1988 and is home to the Mosque of the Three Doors, the oldest known mosque with a sculpted facade.

Unesco describes the mosque as "an architectural masterpiece that served as a model for several other Maghreban mosques".