Barcelona have signed centre back Inigo Martinez from Athletic Bilbao on a free transfer with the Spain international signing a two-year contract, the LaLiga champions said on Wednesday.Martinez leaves Bilbao after six seasons with the Basque club and Barcelona said they will set a 400 million euros ($435.68 million) release clause for the 32-year-old.Martinez arrives with rich experience in LaLiga having made more than 350 appearances in the Spanish top flight with Athletic as well as Real Sociedad."Being strong in the air, a great ball carrier and defensively solid will improve Barca's backline even further, which will also have a left-footed player to call on," the club said in a statement."A veteran of many battles, Inigo Martinez is also known for his leadership and competitive nature."Barcelona have been looking for experience to fill holes in their back line following the departure of veteran defender Jordi Alba while Samuel Umtiti's contract was terminated last week.($1 = 0.9181 euros)