For the second time in 72 hours, an ETA bomb has caused substantial damage to socialist party offices in the Basque country.

Last night's bomb went off at 3.25am, just under an hour after an ETA representative phoned in an official warning to the DYA highway information service at 2.32am.

This gave security forces sufficient time to cordon off the area and evacuate neighbouring buildings. Some of these, as well as several cars parked outside the office, were also damaged by the blast.

There have been six previous attacks on the Elgoibar socialist HQ, the latest of which occurred last December when a burning tyre left on the pavement outside shattered several windows and caused significant smoke damage. Since then, the centre has been closed for renovation.

This is the sixth attack by ETA on the socialist party since the official end of the ceasefire last June, and the second in 72 hours after a similar attack in Bilbao's La Peña district last Thursday.