ETA declared a ceasefire in 2011 but had not surrendered its remaining arms
Nearly three-and-a-half tonnes of arms and explosives have been handed over to French police by the Basque separatist group ETA.
France's prime minister says he welcomes the surrender, which follows more than 40 years of violence aimed at splitting from Spain.
Former ETA leader Arnaldo Otegi says the group is now promising to pursue independence through democratic means.
Earlier, The Basque separatist group gave French police a list of 12 arms dumps in south-western France.
It follows an announcement from the militant group that it would hand over all its remaining weapons..
ETA (Euskadi Ta Askatasuna - Basque Country and Freedom) declared a ceasefire in 2011 but had not surrendered its remaining arms.
French authorities have welcomed the disarmament saying the move marks "an undeniably important day."
The group killed more than 850 people in its attempt to carve out an independent Basque state straddling northern Spain and southwest France.
"This stage of neutralising an arsenal of arms and explosives is a major step," said French Interior Minister Matthias Fekl.
"As the locations are progressively identified, the security forces will carry out operations to secure these sites and secure arms and explosives that may be found there," he said.
The weapons caches could include about 130 handguns and two tonnes of explosives, according to French anti-terrorism experts.
The handover will not mean the end of the group as a political entity, but will end an era of political violence in Western Europe.
In recent years the group has sought to negotiate its dissolution in exchange for amnesties or improved prison conditions for roughly 350 members in Spanish and French prisons.
It is not yet clear if the disarmament process will receive the backing of the Spanish and French governments – both of which have taken a firm line up to now.
A Spanish government source told the Reuters news agency that Madrid did not believe the group would hand over all its arms, while Spain's state prosecutor has asked the High Court to examine those surrendered as possible murder weapons used in unresolved cases.
Inigo Mendez de Vigo, Spain’s culture minister and its government spokesman said on Saturday that the group could expect “nothing” in return for disarming.
“It will not reap any political advantage or profit,” said Inigo Mendez de Vigo.
“May it disarm, may it dissolve, may it ask forgiveness and help to clear up the crimes which have not been resolved,” he said.
ETA was founded in 1959 out of anger at the political and cultural repression under Spanish dictator, General Francisco Franco.
The group’s first known victim was a secret police chief in San Sebastian in 1968 and its last a French policemen shot in 2010.
ETA's first revolutionary gesture was to fly the banned 'ikurrina', the red and green Basque flag.
The campaign escalated in the 1960s into violence and in 1973 the group was responsible for assassinating Franco’s heir apparent - by packing an underground tunnel full of explosives and detonating as his car passed overhead.
Other attacks - including a 1987 car bomb at a Barcelona supermarket, which killed 21 including a pregnant woman and two children - horrified Spaniards and drew international outrage.
An event is being planned in the French Basque city of Bayonne this afternoon to mark what celebrants are calling "Disarmament Day."
A counter-event was held yesterday in the Basque city of Vitoria which included a ceremony for "the protagonists of ETA's defeat".
Sinn Féin President Gerry Adams has since welcomed the news that ETA has now completed the process of putting its weapons beyond use.
He said "The decision by ETA to complete the process of putting its weapons beyond use is historic.
"It creates a unique opportunity which the Spanish and French governments, and the political parties in the region, must urgently grasp.
"I want to congratulate all of those involved in this initiative. It is clear evidence of the desire of the pro-independence parties in the Basque country to continue to build the peace process.
"The Basque people have repeatedly demonstrated in elections and on the streets their support for a peaceful resolution of the conflict in that region. The initiative by ETA is an opportunity that must not be squandered."