"ETA has decided to declare a permanent and general ceasefire which will be verifiable by the international community," it said in text, voice and video statements distributed to media in Basque, Spanish and English.
"This is ETA´s firm commitment towards a process to achieve a lasting resolution and towards an end to the armed confrontation."[break]
A video showed three ETA members in white hoods and black berets, sitting in front of a table and reading the statement out in the Basque and Spanish languages.
Behind them on the wall hung the ETA symbol of a snake wrapped around an axe, which represents armed struggle.
It is the first time that ETA has unilaterally declared a permanent ceasefire in its campaign of bombings and shootings, which has claimed the lives of 829 people in more than 40 years.
There was no immediate reaction from the government. Deputy Prime Minister Alfredo Perez Rubalcaba, who is also interior minister, called an early-afternoon news conference.
ETA had also announced what it described as a permanent ceasefire in March 2006 within the framework of negotiations with Madrid.
But in December 2006, ETA fighters set off a bomb in the carpark of Madrid-Barajas airport, killing two men. Six months later it formally called off the ceasefire.
"It is time to act with historic responsibility. ETA calls upon those governing Spain and France to end all repressive measures and to leave aside for once and for all their position of denial towards the Basque Country," the latest statement said.
"ETA will continue its indefatigable struggle and efforts to promote and to bring to a conclusion the democratic process until there is a truly democratic situation in the Basque Country."
ETA released a series of declarations in September last year proposing an end to violence and calling for international mediation.
But the Spanish government dismissed them, insisting on a definitive, verifiable ceasefire.
Spanish authorities believe ETA has been severely weakened after its security forces in cooperation with other countries, particularly France, repeatedly decapitated the group in raids on the leadership.
But ETA has also come under severe pressure from within.
The group´s political wing, Batasuna was ruled illegal in 2003 due to its links with ETA.
And it has called on ETA to declare a permanent, verifiable ceasefire in an effort to get the ban on its activities lifted so it can take part in municipal elections in May this year.
ETA was formed on July 31, 1959 during the dictatorship of general Francisco Franco by a group of Basque nationalist students.
On June 7, 1968, ETA shot and killed the police chief of the Basque coastal city of San Sebastian in the first deadly attack for which it claimed responsibility.
The Spanish government however has dated the first attack to June 27, 1960, when an incendiary bomb exploded in a station in San Sebastian and killed a baby.
ETA assassinated Franco´s prime minister and presumed successor Admiral Luis Carrero Blanco on December 20, 1973. He was killed instantly when his car drove over explosives planted by ETA in Madrid, sending the vehicle high into the air.
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