Spain'sHome Secretary (Interior Minister) Jaime Mayor Oreja confirmed last night that an investigation is under way in to an alleged ETA plot to target Majorca with a car bomb this summer during the Spanish royal family's annual summer holiday on the island. Oreja said last night that he has received no confirmation about the terrorist attack by the Basque separatist group and that at the moment it is nothing more than a theory. Oreja revealed that the police investigating has yet to confirm exactly what the terrorists' intention were. It was reported yesterday in the newspaper ABC that on August 15, the Guardia Civil in Huelva intercepted a high powered car bomb driven by two ETA terrorists who were heading for Valencia to catch the ferry to Palma. Oreja was also quick to stress that there is no reason to assume that ETA was planning another attempt to assassinate King Juan Carlos. A previous attempt five years ago was smashed by police in Palma after a tip-off from French security forces just hours before the assassination attempt was due to be carried out in Porto Pi. But Oreja admitted that the terrorists were probably up to no good, but added that there is still a lack of solid evidence to confirm that the car packed with explosives was heading to Majorca. Sources for the special security forces which guard the royal family in Majorca every summer, said yesterday that it is practically impossible to drive a car bomb off a ferry in Palma during the summer when security is extremely tight. However five years ago, when the assassination attempt was smashed in the middle of summer, a French registered yacht chartered by the head of the Majorca ETA unit, was found moored in the Port of Alcudia, packed with weapons, explosives and ammunition. ut to come by ferry, the vehicles would have had to have passed through at least four police security checks in Valencia and Palma.