Basque separatist group ETA, the last armed insurgent group in Western Europe, is set to announce its official dissolution following a conference on Friday in southern France, marking the end of half a century of terrorist violence.

The town of Cambo-les-Bains, some 10 kilometres from the Spanish border in south-western France, will host an international conference to be attended by civil society representatives and political leaders.

The participants at the conference will together draft and agree upon a statement that will be read out at the event and will set the stage for the definitive dissolution of ETA. The group itself will then confirm its disbandment in a separate, final declaration.

The meeting was brokered in large part by the International Contact Group (GIC), a panel of veteran politicians and negotiators who have for years worked to facilitate political dialogue with ETA, along with various other organizations.

ETA, an acronym for "Euskadi ta Askatasuna" (Basque Homeland and Liberty), was formed on July 31, 1959 during the dictatorship of Francisco Franco in Spain.

The group demanded the creation of an independent state formed by the northern Basque province of Spain, as well as the neighbouring province of Navarra and parts of southern France.

According to the Spanish Interior Ministry, ETA killed 864 people and carried out almost 300 unsolved crimes and about 100 kidnappings over half a century of armed activities.

ETA announced the end of its armed struggle for an independent Basque State in October 2011.

In April of last year, ETA publicly declared its disarmament, a move met with scepticism by the Spanish central government as well as victims' associations.

The group's impending disbandment in early May would mark the third and final step in closing one of the darkest chapters in Spain's recent history.

Spanish Prime Minister Mariano Rajoy has said that ETA will not obtain "any advantage for disappearing", alluding to the group's request to free imprisoned ETA activists, or bring them closer to home from their current prisons in distant locations of Spain.

Meanwhile, various victims' groups - comprising people injured in terrorist attacks in Spain, their loved ones and the families of those killed - have rejected ETA's declarations and disarmament as a cynical attempt to rewrite their violent history.

When the Irish Republican Army (IRA) announced the end of its armed struggle, ETA became the last armed insurgent group in Western Europe.