After the arrivals of Jacob Murphy and Javier Manquillo last week, midfielder Merino becomes the fifth player to join the Magpies this summer.

Born in Pamplona, he made more than 60 appearances for hometown club Osasuna before moving to Dortmund at the end of the 2015/16 campaign.

He featured nine times for die Schwarzgelben last term, and also figured for Spain at June’s European Under-21 Championship in Poland, where Albert Celades’ side were runners-up.

Merino – who turned 21 during the tournament – said: "It feels good and I'm very happy to be here, to be part of this club. I'm looking forward to touching the ball, meeting my new team-mates and starting to play football.

"I know it's a great club and a really nice city. I had different options but I think this is the right place for me to play."

Manager Rafa Benítez added: "Mikel is a midfielder with talent, an under-21 international for Spain. He's a good size, has quality on the ball and he's very, very focused and professional. Hopefully he's the kind of player we can improve a lot - he certainly has the mentality to get better and better.

“He comes from a top side in Dortmund and although he did not play too much last season, he was signed as a young, talented player and to be signed by a club like that shows that he has something good. He has to show what he has, and hopefully he can enjoy playing here for a long time."