Relatives told of their horror after two teenage British charity workers had acid thrown in their faces on the paradise island of Zanzibar.

Katie Gee and Kirstie Trup, both 18, were being flown home tonight after being treated for severe burns following the unprovoked attack.

The best pals had been working as volunteer teachers at an orphanage and were targeted at 7.45pm on Wednesday as they walked back to their hotel through the Stone Town area of the capital Zanzibar City.

Suddenly two men on a moped roared up alongside them on the narrow lane and hurled acid at them, scorching their faces, chests, backs and hands.

The girls were immediately flown by helicopter to hospital in Dar es Salaam, Tanzania, for emergency treatment.

Speaking outside the family home in Hampstead, North London, Katie’s dad Jeremy said: “I spoke to her about three hours after the incident and again about an hour-and-a-half ago.

“We are absolutely devastated. The photographs that I have seen are absolutely horrendous.

“The level of the burns are beyond imagination unless you see the photographs yourself.”

He added: “The girls are expected back on Friday morning when they will be taken straight to hospital where consultants and surgeons are waiting.”

Katie’s distraught mum Nicky said: “Her whole face and body is burnt.”

Kirstie called her mum, Rochelle, after the attack and told her: “I’m scared and I want to come home.”

Rochelle, 49, said: “She was very, very shaken and in shock. They don’t have a clue why someone would do this.

“They’re just two gorgeous, beautiful girls who went out there to try to help children.

“It was a trip they had planned after working hard for their A-levels, before they both went off to university.

“Until the attack they were having the time of their lives. They loved the country, the people – it was an amazing adventure for them.”

Relatives of both girls were gathered today at the home of the Trup family in Hampstead Garden Suburb.

And it was revealed that Katie had been attacked once before during the trip.

She tweeted on July 24: “A Muslim woman just hit me in the street for singing on Ramadan. Is that normal?”

Police are so far refusing to link the acid attack to rising tensions between the predominately Muslim population and Christian minority.

Tanzania’s President Jakaya Kikwete is reported to have visited the girls in hospital and has vowed to find those responsible for the “shameful” attack.