The clashes happened in the town of Zarzis which is linked to Djerba by a long bridge.

There have been protests there for weeks over what's seen as the Tunisian state's slow response to the death of local people in migrant shipwrecks.

The biannual Francophonie summit brings together leaders of mainly French-speaking countries.

Thirty-one heads of state are expected to attend including those of Ivory Coast, Gabon, Rwanda, France and Canada.