A small Turkish-owned tanker at the centre of an oil leak investigation has been released from detention, owner Besiktas Group confirmed on Wednesday.

The 20,000-dwt Lagertha (built 2009) was detained at the port of Tarragona after a discharge was identified off the coast of northwest Spain on 11 February, according to Spain’s ministry of transport.

Besiktas Group has denied that a spill took place but secured the release of the vessel after a €100,000 guarantee, said an official.

The oil discharge, which covered an area of more than 12 km2, was identified by a routine air patrol by Spanish maritime authorities and later confirmed by satellite images, according to the ministry.

The alleged spill happened a day after the ship stopped at the Repsol refinery at La Coruna, according to Kpler tracking data. It was detained five days later after discharge at Tarragona and is now heading back towards the Atlantic with a destination of Bilbao, the data indicated.

“There was no leak… everything was carried out according to Marpol,” said a Besiktas Group official.

“Our lawyers are on it. They will investigate the case with port officials in Spain.”

The Besiktas Group owns 30 ships, two-thirds of them small tankers, according to the VesselsValue database.

The Spanish authorities said that it imposed a penalty of €550,000 after a similar “red-handed” detection of an illegal discharge from another vessel in 2021.