Spain has detained a tanker ship for illegally dumping fuel in waters off the Canary Islands and creating a 55-square km (21 square miles) oil spill, the Transport Ministry said.

Spanish maritime authorities ordered the Liberia-flagged Aldan to dock in the southern port of Almeria last Sunday after the European Union’s Maritime Safety Agency detected the spill through satellite imagery.

Refinitiv shipping data showed the Aldan, which had been heading eastwards through the Mediterranean to Greece, diverted to Almeria on Sunday. As of Thursday evening it was still there.

The ship’s manager must pay a 600,000 euro ($713,640) fine to release the vessel, the ministry said, adding the amount was a record high for Spain.

The Aldan’s manager is Greece-based Eurotankers Inc, according to Refinitiv data. Eurotankers did not respond to a request for comment.

Source: Reuters (Reporting by Emma Pinedo and Nathan Allen. Editing by Jane Merriman and David Evans)