Athletic Bilbao have signed Gorka Elustondo from Basque rivals Real Sociedad.

The 28-year-old, who can play in a number of defensive positions, has joined Bilbao on a free transfer after the expiration of his contract.

The former Spanish Under-20 international had been with Sociedad since 2004 – progressing through the youth set-up before making his official first-team debut in 2006.

Elustondo struggled for minutes last season, however, and failed to agree terms on a new contract with David Moyes's side.

It is understood that the Spaniard's deal at San Mames will run until 2017.