The 31-year-old was at United until the summer, when he went to Turkey to sign for Fenerbahce.
Fred has enjoyed a revival of his fortunes in Turkey, shining as one of the most important players for his team.
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Ilicali Hull chief told Sabah: "If I had the right to buy two footballers at the end of the season, I would close my eyes and buy Fred.
"Seri-Fred-Ozan trio would be so good that you can sit and watch it with pleasure."
He then added: "Take (Galatasaray's Fernando) Muslera, welcome to the Premier League."