Arsenal have completed the signing of Spain midfielder Mikel Merino from Real Sociedad for a fee that could reach £31.6m.

The 28-year-old moves to north London on a four-year contract with the option of a further 12 months after the Gunners agreed to pay an initial £27.4m plus £4.2m in add-ons.

"Mikel is a player who will bring us huge quality with his experience and versatility," said manager Mikel Arteta.

Merino was part of the Spain squad who won Euro 2024, featuring in all seven matches in the tournament and scoring a late winner in extra time against Germany in the quarter-final.

He becomes Arsenal's third signing of the transfer window, after the arrival of Italy defender Riccardo Calafiori and Spain goalkeeper David Raya, with the club activating an option to buy him from Brentford following his loan move a year ago.

"Mikel will make our squad significantly stronger, with his technical ability, together with his strong and positive character and personality," added Arteta.

“As we all saw in the summer, Mikel is also a winner, with his strong performances throughout the Euros helping Spain win the tournament."

Merino can operate as a deeper-lying midfielder and it is thought he will complement Declan Rice, who played a 'box-to-box' role at times last season.

He also provides Arsenal boss Arteta with another option to compete with Rice, Jorginho, Thomas Partey and Martin Odegaard in midfield.

Merino has previous experience of the Premier League, having spent a year at Newcastle before moving to Real Sociedad in 2018, where he played alongside Odegaard in 2019-20 when the Norwegian was on loan from Real Madrid.

The new signing, who has 28 international caps, made 45 club appearances in all competitions last season, scoring eight goals.