Cadena SER says Barca are in regular contact with representatives of Onana ahead of the summer market.
Ajax sporting director Marc Overmars has assured Onana he can leave for the right offer - and the Cameroon international feels ready for the next step in his career.
Onana has a deal to 2022 and has also been linked with Chelsea this season.
The 24 year-old spent five years with Barca before leaving in 2015 for Ajax.
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