The environmental group said the heavy fuel oil, which continues to leak from the ship as it lies on the sea bed off Spain after sinking in November, is waste which, under EU law, governments must ensure is properly disposed of.

"At the beginning of the crisis the Spanish government decided to order the ship to sail away from the Spanish coast in violation of (EU waste law)," Greenpeace said in a letter to the EU Commission, which has the power to prosecute member states.

"It is clear that Spain has not taken the necessary measures to ensure an adequate removal or disposal of the waste."

The Commission confirmed it and was looking into the complaint, but that there was "no indication so far that we can establish a breach of legislation", a spokeswoman said.

Spain ordered the ship be towed out to sea rather than risk it coming in to a safe harbour in the northwestern region of Galicia. But it broke in half in rough seas and now lies 3,800 metres (12,500 ft) under the surface posing environmental problems for the coasts of Spain and France.

A Spanish campaign group has also filed a suit in a Galician court over the government's handling of the affair.

Spanish Deputy Prime Minister Rodrigo Rato, appearing on TV yesterday, defended his government's actions.

"In similar cases in Spain and abroad, a ship leaking oil has never been put in a port or the mouth of a river. That's a decision no one would take, for obvious reasons," he told Telemadrid. (Additional reporting by Adrian Croft in Madrid).