The Catalan club's sporting director Andoni Zubizarreta revealed that an offer has been tabled, but refused to disclose specific details about the negotiations.
"Valencia already know our offer and we want to maintain privacy in the negotiations. Of course we have other alternatives if this falls through," he told reporters.
"Hopefully by La Liga's start we have that centre-back position covered. If we wanted a centre-back before now, we would have signed one. We want someone who can put in top performances for many years and that's what we're working on."