This is what the club says:
Arsenal announces today that they have reached an agreement in principle with Barcelona for Cesc Fabregas to move to Spain.
It signals the end of the midfielder's eight-year spell at Arsenal. Fabregas joined the Club from Barcelona as a 16-year-old in September 2003 and made 303 appearances, scoring 57 goals in all competitions.
He holds the records for the youngest Arsenal first team player (16 years and 177 days v Rotherham United (h), 28 October 2003) and the youngest Arsenal first team goalscorer (16 years and 212 days v Wolves (h), 2 December, 2003).
Named as Arsenal Captain in November 2008, Fabregas also became a regular in the Spain national team, making 58 appearances to date.
Arsenal manager Arsène Wenger said: "We have been clear that we didn't want Cesc to leave and that remains the case. However, we understand Cesc's desire to move to his home town club and have now accepted an offer from Barcelona. We thank Cesc for his contribution at Arsenal and wish him future success."
The transfer is subject to the completion of formal legal agreements and registration processes, together with Fabregas agreeing personal terms and passing a medical.