Carlos Saenz de Tejada, 28, and Diego Salva Lezaun, 27, of the paramilitary Civil Guard were killed when their car exploded in the tourist resort in the west of the island.

ETA also claimed responsibility for a similar attack outside a police barracks in the northern city of Burgos July 29 that left 65 people injured.

The bomb attack in the Basque town of Arrigorriaga that killed a policeman was also the work of its operatives, the group said.

Police and ETA supporters clashed in the coastal city of San Sebastian Saturday when police broke up an illegal rally. Two men were arrested.

The most recent bombings coincided with the 50th anniversary of the founding of the group which seeks a sovereign Basque state created out of northern Spain and southern France.

ETA is listed as a terrorist organisation by the EU and the US and blamed for more than 820 deaths since 1968.

Spain's Interior Minister Alfredo Perez Rubalcaba vowed after the Majorca attack that the government would never again negotiate with ETA, but defeat the group with the help of police and the judiciary.