MADRID -- The Basque militant group ETA on Friday offered an unprecedented apology for the pain caused during its more than four decades of armed campaign for independence from Spain and France, and vowed not to return to violence.

ETA, which killed more than 800 people including police, politicians and entrepreneurs, is due to announce its final dissolution early next month, ending one of Europe's last violent nationalist conflicts.

After nearly half a century of car bomb attacks, shootings and kidnappings, the group gave up its violent campaign in 2011. One year ago, the organization also handed over to authorities most of its remaining arsenal.

In a statement published on Friday by Basque newspapers Berria and Gara, ETA acknowledged its responsibility for the pain caused by assassinations, torture, kidnappings and people forced to leave the Basque country, in a vague reference not only to ETA's victims but also to the plight of some of its own militants.

"We want to show our respect to the dead, the injured and the victims that ETA's actions have caused," the statement said. "We really are sorry."

Spain's government, which considers ETA a terrorist organization, welcomed the organization's move but said the apology came too late.

"ETA should have sincerely and unconditionally asked for forgiveness for the damage caused a long time ago," the government of Prime Minister Mariano Rajoy said in a brief note.

It added that Friday's announcement was "nothing more than another consequence of the fortitude of the rule of law that has defeated ETA with the arms of democracy."

Both France and Spain, where the group committed most of its deadly actions, had been demanding an apology and that the group take a further step and disband.

The official Basque regional broadcaster ETB, which has in the past had access to the organization's plans, reported this week that ETA's dissolution would be announced in the first weekend of May.

ETB said that an event to mark the end of ETA -- a Basque-language acronym for Euskadi Ta Askatasuna, meaning Basque Homeland and Freedom -- will be held in southern France before the final announcement by the group.

In Friday's statement, ETA said it is committed "to finally overcome the consequences of the conflict and not to fall into its repetition," adding that "it has been a long time that this political and historical conflict should have had a fair and democratic solution."