Hamid El Mahdaoui, who heads the Badil online news site, was arrested in July at the start of a banned demonstration in the restive northern city of Al-Hoceima.
He was initially sentenced to three months in jail after being found guilty of helping to organise “an unauthorised march” and having “invited” others to take part, according to his website.
On Tuesday an appeals court prolonged his prison term by nine months.
RSF denounced the “incomprehensive” verdict and said it was “appalled” by El Mahdaoui’s increased sentence.
RSF called on Morocco to drop the charges against the journalist and to release him as soon as possible, saying he was only doing his job and that the court had video footage proving his innocence.
And quoting his wife, the watchdog said El Mahdaoui had started a hunger strike to denounce the ruling against him.
In July RSF issued a scathing statement accusing Moroccan authorities of preventing journalists from covering months of unrest and protests in the neglected northern Rif region, particularly in Al-Hoceima.
Moroccan authorities denied the accusations.
El Mahdaoui, who was also fined 20,000 dirhams ($2,120, 1,800 euros) in July, is also accused of “undermining state security” and must appear before court on October 2.
If found guilty on that charge he risks being jailed for up to five years, said RSF.
The Rif protests erupted last October after a fishmonger was crushed to death in a rubbish truck as he tried to retrieve swordfish confiscated for being caught out of season.
Demands for justice later snowballed into a wider social movement named Al-Hirak al-Shaabi, calling for jobs, development and an end to graft.
El Mahdaoui is active on social media and known for his criticism of the government.
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