SUNDAY TIMES WEB DESK: Investigations showed that the suspects had connections with Islamic State fighters in the Middle East, a statement carried by state news agency MAP said.
The suspects, who were arrested on Monday, were not identified but the police statement said one of them is of Algerian origin.
Compared with other countries in North Africa, Morocco has been largely insulated from militant attacks.
The four main suspects arrested in connection with the killing in December of two Scandinavian women near the tourist hub of Marrakech had pledged allegiance to IS in a video.
In April 2011, 17 people were killed in the bombing of a restaurant in Marrakech.
In 2017 and 2018, Morocco said it dismantled 20 militant cells planning attacks in the country.