Three men were arrested on Thursday over the murder of Louisa Vesterager Jespersen, 24, from Denmark, and Maren Ueland, 28, from Norway.

The pair were found dead from knife wounds near a popular tourist spot on Monday.

At least one of the suspects has been linked to an Islamist extremist group.

One person had already been arrested on Monday, hours after the bodies of the two women were discovered with injuries to their necks.

Police also supplied photos of the three other suspects, prompting a 72-hour manhunt. Moroccan news outlet 2M said they were shepherds, and had been arrested in the city of Marrakesh on Thursday morning.

After the prime minister's statement, Denmark's PET intelligence agency said it was investigating a video circulating online, which appeared to show one of the two women being murdered.

In the video, the words "this is in revenge for our brothers in Hajin" are heard, a reference to a stronghold of so-called Islamic State in eastern Syria that was seized by US-backed forces earlier this week.

"We cannot say anything at this point about the video's authenticity," PET said, contradicting earlier reports that it had been verified.

Reuters news agency quoted a police source as saying that the video appeared to have been filmed in a different place from where the bodies were found.

"We do not know the circumstances, but there are many indications that the cruel killing may be a terrorist act," Mr Rasmussen said on Thursday.

 Moroccan police released a photo of the three suspects

Ms Jespersen and Ms Ueland had travelled together to Morocco for a month-long holiday on 9 December, including a trip in the Atlas Mountains.

They had been hiking in area near Imil, close to Africa's highest mountain peak Mount Toubkal - an area popular with hikers and climbers. They were found dead inside the tent they shared.

Norwegian Prime Minister Erna Solberg decried the "brutal and meaningless attack on innocent people", and said she had trust in the Moroccan authorities to find those responsible.

Maren Ueland's mother Irene told public broadcaster NRK that the pair had been studying together at the University of South-Eastern Norway. Both are reported to have been experienced with outdoor activities, and to have prepared well for the hiking trip, which they took without a local guide.

Is there a jihadist threat in Morocco?

By BBC Monitoring

Morocco has been largely spared the jihadist violence seen in other countries in North Africa since deadly bombings in Casablanca killed at least 30 people in 2003.

The country enacted stiff anti-terrorism legislation to address the threat from its own nationals returning home after fighting for Islamic State group (IS) in Syria and Iraq - after an estimated 1,600 Moroccans joined jihadist groups there in 2015

Jihadists of Moroccan origin have also been involved in terrorist attacks in recent years in Belgium and France.

In terms of jihadist presence in Morocco, both Islamic State and its rival al-Qaeda have failed to establish themselves in the country. But this does not rule out the possibility of attacks by sympathisers or operatives who believe it is their duty to act.