A Dutch journalist working in Morocco has been ordered to leave the country in a move believed to have been prompted by his coverage of the crisis in the Rif region.

NRC reported that Gerard van der Aa, who freelanced for the newspaper and other media outlets, was arrested four days after returning to the country and told he was working illegally. He was due to return to Europe from the Spanish exclave of Melilla on Monday.

Van der Aa said he was working undercover because the Moroccan government no longer accredited foreign correspondents, but had previously had no trouble reporting from the country without an official licence. He has also written articles on alcohol abuse and illegal migration.

The Berber-dominated Rif region has become a focal point of unrest since 2016, when a fishmonger was crushed to death while trying to recover fish from a rubbish truck that had been confiscated by police.

The incident spawned the protest movement Hirak, whose leader Nasser Zefzafi was jailed for 20 years by a court in Casablanca last June for offences including threatening national unity. Tens of thousands of people subsequently took to the streets to demonstrate against the trial and sentence.

Van der Aa one of several Dutch journalists who have been barred from working in Morocco in recent years. In 2015 Radio 1 journalist Rik Goverde was ordered to leave the country at short notice, while two years later freelance reporter Sjoukje Rietbroek said her work had been made impossible.

NRC reporter Koen Greven and photographer José Colon said they were followed by security service agents and told to leave while working in the Rif region in the summer of 2018.