In a statement ETA called on the Spanish and French governments to respond with “a process of direct dialogue”.
The declaration, if followed through, would bring an end to ETA’s campaign of violence, which has spanned 40 years and killed more than 800 people.
The government has not yet responded to the announcement. Spain’s Socialist government has continued to insist that it will not negotiate on demands for Basque self-determination until ETA disbands.
ETA has been badly weakened by a security crackdown in recent years and the halt to armed conflict is seen by many as them bowing to the inevitable.
The declaration follows a conference this week in the Basque Country, attended by international statesmen including former UN Secretary General Kofi Annan, and protagonists in the Northern Ireland peace process.
They called on Eta to lay down its arms.
In its statement, Eta said “a new political age is opening” in the Basque Country.
“We face a historic opportunity to obtain a just and democratic solution to the age-old political conflict,” it said.
“Eta has decided on the definitive cessation of its armed activity. Eta makes a call to the governments of Spain and France to open a process of direct dialogue which has as its aim the resolution of the consequences of the conflict and thus the conclusion of the armed conflict. With this historic declaration, Eta demonstrates its clear, firm and definitive purpose.”
ETA has been trying to get out of the terror business for some time. In September 2010, it announced a decision not to carry out further attacks.
In January this year, it declared a permanent and “internationally verifiable” ceasefire.
A previous ‘permanent’ceasefire was broken by ETA when they bombed Madrid Airport in 2006, killing two people.