Zanzibar: Attackers in the east African island of Zanzibar threw acid into the faces of two young British women late on Wednesday night, the first such assault against foreigners in the popular tourist destination, police said on Thursday.

Two men on a moped threw the acid at the 18-year-old women as they strolled through the streets of Stone Town, the historical centre of the capital of the semi-autonomous Tanzanian archipelago, splashing their faces, chests and hands.

“Police in Zanzibar have launched a manhunt, and we ask for public assistance in identifying the attackers,” deputy police commissioner Mkadam Khamis said.

“The motive for the attack on the volunteers aged 18 years, has not been established. Investigations are on until we apprehend the criminals,” Khamis said.

The women were flown to Tanzania’s economic capital Dar Es Salaam for treatment, where their wounds were said to be “not life threatening”, said Saleh Mohammad Jidawi, a senior health ministry official.

Tourism is the main foreign currency earner for Zanzibar, famed for its white-sand beaches and historical buildings in Stone Town, listed as a world heritage site by Unesco.

“It may threaten tourists,” said Abdul Samad, chairman of the Zanzibar Association for Tourism Investors.

There have been a series of attacks in the archipelago, including an acid attack on a Muslim cleric in November, and the shooting dead of a Catholic priest in February. Another priest was shot and wounded in December.