The Danish Intelligence service suspects ISIS is behind the grisly killings of two Scandinavian tourists in the Atlas Mountains in Morocco.
On Thursday, Moroccan police arrested three people it had sought in a manhunt over the murders.
The bodies of 24-year-old Louisa Vesterager Jespersen, from Denmark and 28-year-old Maren Ueland, from Norway were found in the tent they shared in an isolated area near Imlil, on the way to Toubkal, North Africa’s highest peak and a popular hiking destination.
A suspect arrested in Marrakech on Tuesday was a member of a militant group, but authorities did not name the organisation.
Danish intelligence said on Thursday Islamic State could be responsible.
The suspected terrorists are reported to have filmed themselves decapitating one of the tourists.
The Moroccan Bureau for Judicial Investigations said on Thursday that three more suspects had also been arrested in Marrakech.
The evidence discovered so far pointed to a terrorist motive, it said.
Preliminary investigations of a video shared on social media purporting to show the killing of one of the tourists had found that it was shot in a different place from where the bodies were found, a police source told Reuters.
"The video and preliminary investigation according to the Moroccan authorities indicate that the killings may be related to the terrorist organisation Islamic State," the Danish intelligence service said in a statement.
"This is a case of an unusually bestial killing of two totally innocent young women," it said.
Compared to other countries in North Africa, Morocco has been largely insulated from militant attacks.
The most recent took place in April 2011, when around 17 people were killed in a bombing of a restaurant in Marrakech
