Two bombs exploded on the Spanish holiday island of Majorca Sunday - and warning of a third had been given - reported local media, as the militant Basque separatist group ETA seemed to be stepping up its renewed bombing campaign, according to dpa. The twin attacks seemed designed to draw attention more than to harm people. Both contained low levels of explosives and were only detonated after warnings had been given allowing ample time to clear people from the blast sites. No injuries were reported from the blasts. But they came on the same day that ETA claimed responsibility for several recent bombings in Spain. The first of Sunday's bombings occurred at a restaurant on the outskirts of Palma de Majorca, along the road leading from the city centre to the island's airport and near a recreational harbour. The explosive was hidden in a backpack in one of the restaurant's bathrooms. The second explosion came about two hours later, in another restaurant only about 500 metres from the first. According to state broadcaster RNE, police operations were under way in a city centre hotel to find a reported third bomb that had been promised by ETA when it warned of the second bomb. The attacks are another blow to the island's tourism industry and came the same day ETA released a statement to the Basque daily Gara claiming responsibility for several recent bombings, including an attack on Majorca in which two police officers were killed. In its statement, the group said it had carried out the car bomb attack on July 30 in the resort town of Palmanova in Majorca. 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 on 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 on 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 organization by the European Union and the United States 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.