Five men are being held by police over an acid attack on two Hampstead Garden Suburb teenagers on the African island of Zanzibar.

Ham & High: Kirstie Trup. Picture: Facebook.Kirstie Trup. Picture: Facebook. (Image: Archant)

Katie Gee and Kirstie Trup, both 18, are returning home to London today, where they will be helped to overcome their terrifying ordeal by family and friends.

The pair were attacked by men on a motorbike as they walked along a road on the Indian Ocean island on Wednesday night.

Mkadam Khamis, regional police commissioner in Zanzibar, told the Daily Telegraph: “There are five people we have, all men, who we are interrogating over this matter this morning.

“They have not yet been arrested. They are co-operating and answering our questions. Later today maybe there will be a development legally.”

The teenagers were in the last week of a trip as volunteer teachers organised by Kent-based i-to-i Travel when a corrosive substance was thrown at them in an apparently unprovoked attack.

They suffered burns to their faces, hands, legs, backs and necks, The Times reported.

Zanzibar is an archipelago of islands in the Indian Ocean about 22 miles (35km) off the mainland.

The semi-autonomous region of Tanzania is predominantly Muslim and has been the scene of some religious violence in recent years.

Earlier this year two Christian leaders were killed and in November a cleric was treated in hospital after an acid attack.

The attack happened in the Stone Town area of Zanzibar’s eponymous capital city.