Bayonne and Madrid: Basque militant group ETA in effect ended an armed separatist campaign after almost half a century on Saturday, leading French authorities to the sites where it says its caches of weapons, explosives and ammunition are hidden.

ETA, which killed more than 850 people in its attempt to carve out an independent state in northern Spain and south-west France, declared a ceasefire in 2011 but did not give up its remaining arms.

French police officers open a weapons cache in Saint Pee sur Nivelle, south-western France, on April 8. Credit:AP

Founded in 1959 out of anger among Basques at political and cultural repression under General Francisco Franco, ETA (Euskadi Ta Askatasuna - Basque Country and Freedom) gained notoriety as one of Europe's most intractable separatist groups.

Saturday's handover, via intermediaries, of its weapons in the French city of Bayonne will not mean the end of the group as a political entity, but will end an era of political violence in Western Europe.