Celtic target George Baldock this summer. The Parkhead side are long-term admirers of the 28-year-old right-back and he has been on their agenda since Mikael Lustig left the club in 2019.
But Yorkshire Live claim the Blades "wouldn't entertain" a bid of £5m for one of their most important players as they look to secure an instant return to the Premier League next season.
United's hardline stance may be viewed as a surprise to some with Baldock only having one year remaining on his current deal at Bramall Lane.
Celtic are also monitoring Derby County's Nathan Byrne and have been linked Rennes right-back Brandon Soppy in a bid to fill a key position of need.
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