United have turned down a £900,000 offer from Parkhead and have decided in-house that they will not sell another important player to Celtic following the furious reaction of their supporters when Stuart Armstrong and Gary Mackay-Steven were allowed to move ahead of the League Cup final last season.
With Ciftci refusing to extend his contract which has one year to run, it would be in United’s interests to cash in now and they are clearly hoping that interest from Middlesbrough will be followed by a serious bid.
Celtic may not be about to go away, however, as assistant manager Collins said: “He has obviously played against us many times last year, he’s a big striker, he’s strong, he’s powerful and he’s got technique as well. We like him.
“I believe there is an approach but that’s all I’ve heard.
“We’re looking to strengthen the squad but unfortunately we can’t talk about other players at other clubs. It would be unfair and disrespectful to the other clubs to do that but we are looking for new players.
“We are juggling lots of balls, there are lots of players we have been mentioned with. That is always going to be the case. We want to strengthen all over. It’s not fair for me to talk about the names of individuals at clubs. That would be disrespectful to their managers – and the players. But we are on the look-out.”
Ciftci is facing a lengthy suspension if found guilty of an excessive misconduct charge for allegedly biting Dundee’s Jim McAlister at the end of last season. He has been ordered to attend a hearing at Hampden on 20 July and any punishment would follow him to the English Championship if he did move to Middlesbrough.