A mass grave containing the decapitated bodies of at least 12 people has been discovered near a hotel used by foreigners that was overrun by Islamic State militants in Mozambique.

Palma, a coastal town in Mozambique’s northern Cabo Delgado province, was attacked by militants wielding machetes, assault rifles and heavy weapons on March 24.

The 12 bodies were found under a large mango tree near the entrance of the Amarula Hotel, an establishment favoured by foreign contractors working on a nearby natural gas project run by the French oil giant Total.

“They were tied up and beheaded here,” Pedro da Silva, a police commander, said in footage broadcast by Mozambique’s TVM channel on Wednesday.

“It’s hard to know their nationalities, but we know that Aamaroula is a hotel that often hosts foreigners, and when the insurgents came most foreigners thought Amarula was the safest place to go, so they all came here.”

“There was security but the insurgents were stronger so they managed to break in and take 12 foreigners, tie their hands behind their backs and decapitated them all.”

Da Silva said he believed the victims were foreigners because the bodies were white but that he could not speculate on their nationalities. Mozambique has citizens of all colours including whites.

However, a source familiar with the operation in Pemba, the provincial capital of Cabo Delgado, said that the victims were black. The source said the bodies were so decomposed they would be difficult to identify.