The 22-year-old leaves St. James’ Park for an undisclosed fee having made 24 Premier League appearances for the Magpies, scoring once in a 1-0 victory over Crystal Palace.

Merino initially joined Newcastle United on loan from Borussia Dortmund last summer before the option of a permanent transfer was exercised in October 2017.

Mikel Merino pictured during his solitary Emirates FA Cup appearance - a win against Luton Town in January 2018

The midfielder’s new club, which is based in San Sebastián – just over 50 miles from his hometown of Pamplona, finished 12th in the Spanish top flight last season.

Everyone at Newcastle United wishes the player the best for the future.​