Tunisian police used tear gas on hundreds of demonstrators on Friday as they clashed when protesters tried to reach the southern island of Djerba where the 18th Francophonie summit is due to take place.
The crowds were trying to establish the fate of Tunisian migrants who have been missing for nearly two months.
A makeshift boat carrying 18 Tunisian migrants en route to the Italian coast disappeared during the night of 20-21 September after leaving Zarzis in the south-east. Only eight bodies have since been found since.
Police units were deployed at the entrance to Djerba, an island in southern Tunisia, to prevent the protesters, who came in dozens of cars and motorbikes, from entering.
Ali Kenis is a fisherman from Zarzis and says he is determined to keep the protests going: "We will launch civil disobedience, and close all entry and exit points to Zarzis, and all public and private establishments, so we can isolate the city," he says.
Families and relatives of the missing migrants, supported by the inhabitants and fishermen of Zarzis, organised several demonstrations gathering thousands of people to push the authorities to intensify the search for those still missing.
A general strike was held in the city on 18 October to demand an investigation into the sinking of the boat and the hasty burial of some of the bodies in a private cemetery ("Jardin d'Afrique"), usually reserved for sub-Saharan migrants.