"ETA announces it will make 'significant contributions' to the process 'without delay'," said the Basque newspaper Gara, the usual mouthpiece for statements by the group in Spain.
In a more detailed statement to be published in Gara , "ETA does an extensive review of events over the past months" and notes that "interesting opportunities for progress have emerged in the Basque Country," the paper said.
ETA is blamed for the deaths of 829 people in a four-decade campaign of shootings and bombings for an independent Basque homeland in northern Spain and southwestern France.
In October 2011 it announced a "definitive end" to armed activity but it has not formally disarmed or disbanded as the Spanish and French governments demand.
Tensions have risen in recent months as ETA prisoners have sought in vain to gain concessions over their conditions, outraging victims' families.
The governments of Spain and France refuse to negotiate with ETA, which is classed as a terrorist organisation by the European Union and the United States.