Spain vowed to bring to justice all those who committed crimes in the name of former Basque separatist group ETA even as its formal dissolution was sealed on Friday with calls for reconciliation.
By disbanding, the group put a definitive end to western Europe's last armed insurgency following more than four decades of killings and kidnappings.
But the Spanish government reiterated its vow to pursue any outstanding cases against members of the group, which is blamed for more than 800 killings.
"ETA's crimes will continue to be investigated, its offences will continue to be tried in the courts, convictions will continue to be issued accordingly and the sentences will continue to be served," conservative Prime Minister Mariano Rajoy said in an address.
"There has not been and will not be any impunity. We owe them nothing and have nothing to thank them for."
Rajoy paid tribute to people the group is accused of killing and the victims' families. He said the group is now accused of killing 853 people.
"They were all murdered unjustly and cruelly," he said.
"We owe a homage to all of them -- to them, their families and the hundreds of Spaniards who survived the terrorist violence but who still suffer the consequences of that cruelty."
Mediators gathered in the French Basque country on Friday for a peace conference to mark ETA's dissolution.
In a closing statement, they said the move must lead to "reconciliation".
ETA's decision marks "a commitment to take part in the democratic process" within Spain's institutions, "which will require reconciliation," South African lawyer Brian Currin said at the conference in Cambo-les-Bains, southwestern France.
In the small village of Oiartzun in the Spanish Basque country, graffiti reading "Thanks ETA" appeared in several locations overnight, according to an AFP journalist at the scene.
The Spanish government has refused to negotiate with ETA, which is classed as a terrorist organisation by the European Union.
ETA "will not get anything in return for announcing its dissolution," Rajoy said.
His allies in Brussels formally welcomed ETA's move.
"There is no place in the European Union for terrorism, arms and guns," said European Commission spokesman Margaritis Schinas.
"The European Union is based on the rule of law."
Northern Ireland's Gerry Adams, the former head of Sinn Fein -- once considered the political wing of the Irish Republican Army -- called on the Madrid government to turn the page.
"In my own view, there is a particular onus on governments, which are the more powerful actors in any conflict, to proactively engage and sustain the conditions for a peace process," he said in a speech at the conference.
He urged the Spanish government to move imprisoned ETA members closer to their families -- a long-standing demand by the separatists and their relatives.
"It would not be a sign of weakness," he said.
But Spanish government spokesman Inigo Mendez de Vigo said "the government will not alter its penitentiary policy."
Spain's former prime minister Jose Luis Rodriguez Zapatero, whose socialist government carried out secret talks with ETA, also defended dialogue.
"The great thing of democracy is to integrate those who have been its worst enemies, it is its moral superiority," he said during a television interview.
On April 20, ETA asked forgiveness from its victims for the first time for the "pain" caused by its decades-long campaign of violence.
Victims' campaigners complained that the call for forgiveness did not extend to those the group considered legitimate targets, such as police officers and politicians.
"ETA was not able to express a word of contrition for all the victims, but Basque society and institutions can do it," said the head of the Basque regional government, Inigo Urkullu, of the nationalist PNV party.