BILBAO, Spain — In a politically risky move aimed at ending Europe's last armed conflict, Spanish Prime Minister Jose Luis Rodriguez Zapatero announced Thursday that he would open peace talks with ETA, the outlawed Basque guerrilla organization.
The talks follow ETA's declaration in March of a "permanent" cease-fire in the group's four-decade fight for independence. Together, the developments represent what many here believe to be the best chance in years for a lasting peace.
Zapatero immediately faced angry criticism from victims organizations and Spain's main opposition party.
"The process is going to be long, hard and difficult," the prime minister said as he announced the talks in Madrid. He offered few details but promised that the government would not make major political concessions to ETA, which many Spaniards consider a terrorist group.
The talks are expected to focus on government demands that ETA fighters disarm and the group's call for Basque prisoners to be moved to jails closer to their hometowns. The Basque separatists also want a voice in determining the future of their region, but Zapatero seemed to rule that out.
The dialogue probably will take place in closed meetings in a European country other than Spain. Zapatero said political parties could expect a progress report in late September.
More than 2 million Basques live in a small wedge of northern Spain near the border with France, sharing a common ethnic background, customs and language. ETA has been fighting for an independent Basque country in its traditional homeland in northern Spain and southern France since the waning years of Gen. Francisco Franco's dictatorship, which ended in 1975.
More than 800 people have been killed in ETA attacks, including police officers, politicians and journalists, and thousands more injured. The violence often reached other parts of Spain, including Madrid.
Putting a definitive end to the conflict would be a major victory for Zapatero, whose Socialist government has confronted Islamist terrorism and tough resistance from the right-wing Popular Party. If the talks fail, the government could fall, and Basque nationalists, invested now in the peace process, might be tempted to make more radical demands.
An organization representing families of ETA victims condemned the government's decision to negotiate, accusing Zapatero of "killing the memory" of the dead. The group held an overnight vigil Thursday in Madrid to protest the possibility of talks and attempted to deliver to parliament a wreath of white carnations stained with red paint.
"It is monstrous that an elected, legal government agreed to dialogue with a criminal band," said Vidal de Nicolas, a poet in Bilbao and former head of an anti-nationalist Basque organization. "It is as if the jewelers were talking with the jewelry-store robbers."
Opposition leader Mariano Rajoy, head of the Popular Party, said in Madrid that his group would not support the government's plans. Talking with terrorists, he said, is unacceptable.
Polls, however, show general support among Spaniards for negotiating an end to the conflict, even if it means sitting down with guerrilla commanders.
ETA -- which stands for Euskadi Ta Askatasuna in the Basque language, or Basque Homeland and Freedom -- declared cease-fires in 1989 and 1998, but negotiations that followed collapsed.
ETA has not killed anyone in three years, although it continued to set off minor bombs and demand protection money from businesses. Large-scale police operations in Spain and France have severely cut into the group's ability to carry out attacks.
In addition, public outrage over train bombings by Islamist militants on March 11, 2004, forced some ETA leaders to rethink their strategy.
Txema Montero, an attorney in Bilbao who served as an advisor to ETA in the 1989 talks but broke with the group over its insistence on armed struggle, said the moment was right for dialogue. He said Zapatero probably could win over his opponents because of the public's general fatigue with violence.
The separatists are "not changing because they've decided they love democracy. They still don't understand democracy the way you and I do, but they did reach the conclusion that things were not working out for them," Montero said. "It's not love but self-interest. We have to try to work with that."
The negotiations with ETA will be accompanied by political talks involving all Basque parties, including ETA's outlawed political wing, Batasuna. These separate talks are aimed at discussing the region's future status.
A number of Basque groups lauded the Spanish government's decision, as did officials of the European Union and France, where Basques also claim a homeland.
Batasuna official Pernando Barrena said the move commits Zapatero to a "respect for the decisions taken by the Basque people." The regional Basque government praised the opening of talks as "positive" and pledged its support.
The Basque Country already enjoys considerable autonomy. The area has its own parliament, police force, schools and taxation powers. But some Basques want more, such as the ability to enter into international trade agreements.
Zapatero's government has been more receptive to expanded regional autonomy, and conservative opponents are afraid the Socialists will give away too much.
Last week, the region of Catalonia approved a referendum that granted itself greater autonomy; opposition leader Rajoy complained that it was the beginning of the end of Spain.