By Vincent West.
BILBAO, Spain, (Reuters) - Basque political parties said on Wednesday they hoped a pledge by militant separatist group ETA to disarm this weekend would draw a line under a decades-long campaign that killed more than 800 people across Spain.
ETA called an end to its bid to establish an independent Basque state in northern Spain and southern France in 2011 but has only handed in part of its arsenal so far.
Politicians from a broad spectrum of parties, including pro-independence and national ones, gathered in the port city of Bilbao on the Basque coast to urge action on ETA's pledge to hand over all its weapons.
"We call on ETA to complete as soon as possible a single act of unilateral, complete, definitive and verified disarmament," Basque Socialist Party representative Rafaela Romero told a news conference.
ETA's disarmament could effectively end Western Europe's last insurgency but it was unclear how it would be organized and if it would be formally accepted.
News that the disarmament would take place on April 8 in Bayonne, France, first came when pro-Basque independence environmental group Bizi told Le Monde newspaper it had been given responsibility for the handover.
Romero said the process should not be conditioned by politics but asked for support from the Spanish and French governments, an international monitoring group, public institutions and civil society.
The Basque parliament is due to vote on Thursday on the proposals.
"We want to give credibility to the announcement, expressed under those conditions. We hope it is successfully completed," Romero said.
The Spanish and French governments have repeatedly rebuffed overtures from ETA to negotiate, refusing to talk unless the group hands over its arsenal.
Madrid has said it will give nothing in exchange for ETA's disarmament and resisted lobbying to move ETA operatives in Spanish prisons to facilities closer to the Basque Country.
The French Interior Ministry has said there could be no negotiation over the terms of a weapons handover.
The campaign by ETA (Euskadi Ta Askatasuna - Basque Country and Freedom) began in the 1950s during the dictatorship of General Francisco Franco, who repressed the Basques politically and culturally, and ETA for decades carried out bombings and assassinations.
Following the return of democracy in Spain, the Basque region gained more autonomy, while its violent tactics also caused public support to wane.
ETA has been severely weakened in recent years by the arrests of hundreds of its members, including its leader, and police seizures of several weapons stashes.
The Popular Party (PP) of Prime Minister Mariano Rajoy was the only major party not to attend the event in Bilbao.
A PP spokeswoman said the party had not been invited but would not have gone if it had been asked.
Amaya Fernandez, PP regional secretary general, told a news conference in the Basque city of Vitoria that the planned disarmament was a way for ETA to "wash away its past and put pressure on democratic governments in Spain and France".
Arnaldo Otegi, leader of far-left Basque pro-independence party EH Bildu, traditionally close to ETA, chided the PP for its resistance.
"In spite of everything they say, ETA's armed violence disappeared many years ago," Otegi said. "As ever, the PP is not in touch with the reality of the country."
(Additional reporting by Inmaculada Sanz; Writing by Isla Binnie; Editing by Julien Toyer and Angus MacSwan)