Greenpeace volunteers gather on Playa de Las Teresitas during a protest of Spain's decision to explore plans for oil and gas off the coast of the Canary and Baleares Islands on June 28, 2014 in Tenerife

Spain's government sparked an outcry Thursday by giving oil group Repsol the all-clear to explore for oil and gas off the coast of the tourism-dependent Canary Islands.

The industry ministry gave Repsol a three-year licence to drill in three sites some 50 kilometres (30 miles) off the coast of the Spanish archipelago, which lies off the northwest coast of Africa.

The exploration, approved in a decision published Wednesday in the official state bulletin, is opposed by the local government and by environmental groups, which warn of damaging consequences of any oil spill or from vibrations caused by the exploration.

"The Canaries are not for sale," said Paulino Rivero, president of the Canary Islands' regional centre-right nationalist coalition government, Coalicion Canaria.

He called on Spanish Prime Minister Mariano Rajoy, of the conservative Popular Party, to intervene in the affair.

Rivero warned the central government not to show preferential treatment to the Balearic Islands, a region run by the ruling Popular Party and which is also the target of an project.

Otherwise, he said, there could be a "break in institutional relations" between the Canary Islands and the central government.

Rajoy last week said his would not allow oil exploration off the Balearic Islands if it presented the slightist environmental risk.

Friends of the Earth, Greenpeace, WWF, Ecologistas en Accion and SEO Birdlife have announced they will appeal the oil exploration decision in Spanish and European courts, saying the process was littered with "irregularities".

Spain's environment ministry had given a favourable environmental impact statement to the exploration in May, saying its decision was backed by "rigorous" scientific research.

The exploration licence granted by the Spanish industry ministry ordered Repsol to provide a guarantee of 20 million euros ($27 million) to cover its "environmental responsibilities".

Repsol was also required to halt its operations in the case of seismic activity exceeding an amplitude of 4.5 on the Richter scale.

Of all the advanced economies in the OECD, Spain is the most reliant on energy imports, buying 99.9 percent of its oil and gas.