Some 200 members of Morocco's pro-reform February 20 protest movement gathered outside the justice ministry in Rabat on Wednesday to demand the release of political prisoners, an AFP journalist reported.
The protesters were joined by hundreds of unemployed graduates, who hold near-daily demonstrations in the capital.
"Free the February 20 activists," and "Peaceful protests are a right," were among the slogans they chanted.
"The February 20 movement is peaceful, it has never called for violence. We will continue to protest until our comrades are freed," one of the protesters told AFP.
In recent months a group of 18 Moroccan NGOs has called for the release of all political prisoners, among them around 60 activists with the February 20 youth movement which was born out of the Arab Spring protests that erupted across the region in early 2011.
Charges on which the political prisoners have been jailed include taking part in non-authorised protests, violence against the security forces and drug trafficking.
Several of them have been on hunger strike in protest of their detention, the Moroccan Association of Human Rights said last month.
Limited political reforms introduced in 2011 and elections held that year helped defuse the mass street protests that swept Morocco's main cities, but discontent in the kingdom remains over high unemployment, along with widespread poverty and corruption.