The NGO members were planning to head to the southwestern Algerian city of Tindouf on Tuesday to discuss issues related to Western Sahara.
Ridha al-Tawejni, chairman of the Moroccan Sahara Association, told an Aljazeera reporter that the Algerian authorities did not want to listen to the organisation's demands.
"We don't understand the attitude of the Algerian authorities. When we embarked there was no problem. Then, just before we were due to fly off we got a call saying an order had come through not to let us fly," said Tawejni.
He had been due to accompany members of the association and several journalists, including Spaniards and a Dutchman, on the Air Algeria flight.
The association indicated it had been set to call for the repatriation of the remains of Moroccans who have died in camps at Tindouf, home to thousands of displaced mainly Sahrawi refugees and scene of an uprising earlier this year over living conditions.
An association flight in June was similarly prevented from flying to Tindouf, stopped on that occasion at Algiers.
"We don't understand the attitude of the Algerian authorities"
Moroccan Sahara Association
The association had hoped to call on the Algerian Defence Ministry to return the bodies of victims of alleged torture and added it had also intended to fly in up to 1000 kilos of food and educational aid.
"We wanted to send out a message to the Moroccan people that these people are our family," Tawejni told AFP, adding that the Algerian Foreign Ministry had earlier indicated there would be no problems with the flight going ahead as scheduled.
"Why has Algiers responded in such a fashion?"
Tawejni added another attempt would be made on Wednesday.
Western Sahara, a former Spanish colony, was annexed by Morocco in 1975, but the Algerian-backed Polisario Front has fought a long breakaway struggle.