Moroccan prosecutors have asked for the death penalty for three suspected jihadists who killed a pair of Scandinavian hikers last December.

Danish student Louisa Vesterager Jespersen, 24, and 28-year-old Norwegian Maren Ueland had their throats slit in Morocco's Atlas mountains last year.

Suspected ringleader Abdessamad Ejjoud, 25, and fellow killer Younes Ouaziyad, 27, admitted they had beheaded the girls, while Rachid Afatti, 33, filmed the murders on his phone.

Prosecutors are seeking the maximum sentence for the men, who had sworn allegiance to ISIS, although Morocco has had a freeze on executions since 1993.

Danish student Louisa Vesterager Jespersen (pictured left), 24, and 28-year-old Norwegian Maren Ueland (right) had their throats slit while camping in the Atlas mountains in December

Prosecutors are seeking the death penalty for Rachid Afatti (left), Younes Ouaziyad (centre) and Abdessamad Ejjoud (right) after they admitted the killings

They also called for jail terms of between 15 years and life for 21 other defendants, who are on trial before an anti-terror court in Sale, near Rabat.

All but three of those on trial had said they were supporters of the Islamic State (ISIS) group, according to the prosecution.

The three killers of the girls were 'bloodthirsty monsters', the prosecution said, pointing out that an autopsy report had found 23 injuries on Jespersen's decapitated body and seven on that of Ueland.

'I beheaded one of them... I regret it,' former street vendor Abdessamad Ejjoud, 25, told the court, blaming co-defendant Younes Ouaziyad for killing the other hiker.

'We loved ISIS and we prayed to God for it,' he said.

Lawyers for the Danish victim's family on Thursday accused authorities of having failed to monitor the activities of some of the suspects before the two women camped in an isolated mountain area had their throats slit.

The brutal killings could have been spared had authorities heeded information on the behaviour of street vendor Ejjoud, they said.

A van carrying the suspects enters the court house in Sale, Morocco, on Thursday

The alleged ringleader, who had been convicted for trying to join ISIS in Syria, was released early from prison in 2015 and went on to meet former inmates and other individuals without checks by authorities, lawyer Khaled El Fataoui said.

He alleged police had been informed of their activities but failed to act.

Lawyer Houssine Raji added that the suspects met in Koranic schools run by cleric Mohamed al-Maghraoui, which had been shut in 2010 under a court decision but ordered reopened in 2012 by the justice minister.

The lawyers demanded that Maghraoui and the then justice minister Mustapha Ramid be summoned for questioning, a request rejected by the court.

Investigators have said the 'cell' was inspired by ISIS ideology, but Morocco's anti-terror chief insisted the accused had no contact with the jihadist group in conflict zones.

ISIS has never claimed responsibility for the murders.