Morocco's Central Bureau of Judicial Investigations says the latest arrests were made Thursday and Friday across the country. With four other men arrested earlier, that brings the total number of suspects in the case to 13.
Moroccan investigators say those arrested were carrying arms and "suspicious materials" used in making explosives. The bodies of the women from Norway and Denmark were found near the village of Imlil, a starting point for treks to Mount Toubkal, North Africa's highest peak.
Moroccan authorities say a plane carrying the caskets of the two European tourists slain in the Atlas Mountains has taken off from Casablanca for Denmark.
Authorities in Morocco consider the killings a terrorist act and have arrested four men.
The victims have been identified as 24-year-old Louisa Vesterager Jespersen of Denmark and 28-year-old Maren Ueland of Norway. They lived in southern Norway, where they attended university.
Norwegian criminal investigators are trying to map the women's activities before their departure for the village of Imlil, a frequent starting point for treks to Mount Toubkal, North Africa's highest peak.
The women's bodies were found Monday 10 kilometers (6.2 miles) from the village with stab wounds on their necks.
Norwegian police says a video that allegedly shows the slaying of a Scandinavian university student in a remote part of Morocco's Atlas Mountains is likely authentic.
Norway's National Criminal Investigation Service (NCIS) has been investigating the footage circulating on social media.
"There is no concrete evidence indicating the video is not real," it said.
Four men have been detained in Morocco in the slayings of two female tourists from Denmark and Norway who were hiking in the Atlas Mountains. Authorities in Morocco consider the killings a terrorist act. The women's bodies were discovered Monday with stab wounds in their necks.
Morocco is generally considered safe for tourists but it has been routing out Islamic extremists for years.