The France international is a major target for the Old Trafford club before the Premier League transfer window closes on August 8, according to Le 10 Sport.
Negotiations are underway between the two clubs over a potential transfer, and United are willing to pay €50 million for his services.
The Catalan club have set a price tag of €60m but the two sides could meet in the middle to facilitate a move.
The outlet adds that Manchester City also made enquiries for the centre-back earlier this summer, but are yet to take their interest any further.
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