SAN SEBASTIAN, Spain (Reuters) - International leaders meeting in Spain's Basque region appealed to separatist group ETA Monday to announce an end to its four decades of violent struggle for independence, and called for France and Spain to have talks with ETA if it did so.

The last of Western Europe's major armed guerrilla groups, ETA is increasingly coming under pressure from disenchanted ETA prisoners and political allies to go further than a "permanent" ceasefire declared in January. The group has killed more than 850 people in bombings and shootings since 1968.

High-profile international figures who helped broker solutions to the Northern Ireland conflict and South Africa's apartheid system attended a conference Monday in San Sebastian in the Basque country.

Former Irish Prime Minister Bertie Ahern welcomed ETA's truce gesture and said, "We believe it is possible after more than 50 years of violence to reach a fair and lasting peace.

"We call on ETA to make a public declaration of a definitive end to armed activity and call for dialogue with the governments of Spain and France to talk about the consequences of the conflict," he said.

Organized by Basque citizens' group Lokarri, the three-day meeting was seen as a chance for ETA to renounce bloodshed.

ETA, which puts out statements from time to time, often through the Basque newspaper Gara, has not responded to media reports suggesting it would be receptive to the appeals.

In July, it issued a statement in which it said it was prepared to "deepen the path taken" to achieve peace. The Spanish government has repeatedly said it will not negotiate with ETA unless it definitively lays down arms and disbands.

The conference was a prop offered to ETA to enable it to quickly justify and declare a definitive disarmament, sources close to the PNV were quoted as saying in the daily El Pais.

SCRUTINY

The wording of any ETA statement will be scrutinized for commitments to disarm since the group has used the term "permanent" ceasefire in the past, then returned to violence.

"If ETA and those close to it need this conference to stage their end, let them make the most of this opportunity," said the head of the Basque regional government, Socialist Patxi Lopez.

ETA wants an independent Basque homeland comprising the Spanish and French Basque regions and the Spanish region of Navarre.

Spain's Socialist government did not support the conference but the mainstream, non-violent Basque nationalist party, the PNV, helped in the preparation of the gathering.

Former U.N. General Secretary Annan and Gerry Adams, head of the Irish Sinn Fein party that was the political wing of the now-defunct guerrilla Irish Republican Army, were among conference participants. Former British prime minister Tony Blair sent his ex-chief of staff Jonathan Powell to the meeting.

Many Spanish politicians and much of the media reacted skeptically to the suggestion ETA could renounce violence for good, with some angry about international peace brokers coming to Spain to discuss ETA.

"They don't have a bloody clue what country they are in or what type of conflict has gone on," said Esteban Gonzalez Pons, of the People's Party, which is on course for a landslide victory in a general election next month, polls indicate.

Madrid held peace talks with the organization after the Socialist government first came to power in 2004 but called them off when the group detonated a large car bomb at Madrid's airport in December 2006, killing two people.

(Writing by Sarah Morris; Editing by Mark Heinrich)