Basque separatist group ETA has announced it is fully disbanding, marking the definitive end to its deadly independence campaign and to western Europe's last armed insurgency.
The group never met its political targets, and by 2009, a survey carried out by the University of the Basque Country found that only one percent of Basque respondents said they totally supported ETA.
The announcement, however, does not end the Basque Country's conflict with Spain and France, the letter added.
"Eta has made a decision to end its historic cycle and role, bringing to a close its journey", said the text, which was published by Spanish newspapers.
The militant group ETA - which killed about 850 people during its bid to force independence from Spain - says it has now "completely dissolved all its structures". To many people's surprise, the group continued its campaign of violence after the introduction of democracy and the 1978 constitution, which granted substantial autonomous powers to the Basque region.
Government spokesman Inigo Mendez de Vigo said Spain would continue to pursue suspects in crimes attributed to ETA.
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ETA assured on Wednesday they dissolved all structures and stopped its political initiative. The letter was sent to figures such as former United Nations secretary general Kofi Annan to reassure them that ETA was firm in its decision to disband, the representative said.
"ETA obtained nothing through its promise to stop killing, and it will obtain nothing by announcing what they call dissolution", he said.
Created in 1959 at the height of Francisco Franco's dictatorship, ETA is blamed for the deaths of at least 829 people.
The group has demanded that prisoners be moved to prisons closer to their families after the end of ETA, AFP news agency reported on Wednesday.
The separatist group issued a partial apology last month, in which it acknowledged the harm done and apologized to some of its victims - but not to those it considered legitimate such as police.
Consuelo Ordonez (3rdR), sister of Spanish Popular Party (PP) councilor Gregorio Ordonez killed by ETA, Maite Pagazaurtundua (C), sister of assassinated Joseba Pagazaurtundua, South East Fermanagh Foundation (SEFF) director Kenny Donaldson (L) hold placards during a press conference by the Association of the Victims of Terrorism of Basque Country (Covite) in the Spanish Basque city of San Sebastian. The militant group itself had hinted that a final declaration would arrive this week.