The killing of two Scandinavian tourists in Morocco is being considered as an act of terror, Denmark's prime minister has said.

The bodies of Louisa Vesterager Jespersen (24) from Denmark and 28-year-old Norwegian Maren Ueland were found in an isolated area of the High Atlas mountains in Morocco on Monday by other tourists.

Danish intelligence have revealed that Islamic State may be responsible for the murders, saying: "The video and preliminary investigation according to the Moroccan authorities indicate that the killings may be related to the terrorist organisation."

Denmark's Prime Minister Lars Lokke Rasmussen said the killings can be considered "politically motivated and thus an act of terror."

Morocco's prosecutor said on Wednesday one of the men suspected of killing the women belongs to a militant group but stopped short of naming which.

The man was arrested on Tuesday in Marrakech, Morocco's main tourist hub. Three other suspects were arrested on Thursday following a extensive manhunt.

Danish authorities have authenticated a video shared on social media - showing one of the tourists screaming while a man fatally cuts her neck with a knife.

The video appears to indicate the killing happened in a different location to where their bodies were found.

A source from Imlil, a village six miles away from where the women were found, said one of the victims was found dead inside her tent while another was found outside.

Moroccan news reports stated investigators have video surveillance footage showing three suspects putting up a tent near the victims' tent and leaving the area after the killings.

Morocco has been largely insulated from the militant attacks seen in other North African countries and has stepped up its effort to counter militant groups by establishing its own version of the FBI.

Imlil is a starting point for trekking and climbing tours of Mount Toubkal, the highest summit in North Africa.