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Gary Mackay-Steven joined Dundee United from Airdrie in 2011

Dundee United manager Jackie McNamara has criticised Celtic counterpart Ronnie Deila as Gary Mackay-Steven agreed a switch to the Glasgow club.

The 24-year-old Scotland international, whose United deal ends in the summer, has signed a pre-contract agreement.

But Deila spoke of his desire to agree a fee for the winger during January instead of waiting until May.

"He's under contract, he's our player and it's nothing to do with Ronnie at the moment," said McNamara.

United had rejected three bids from Sheffield United to secure the player during January and it is still open for Celtic to agree a fee to take Mackay-Steven during the current transfer window.

Deila spoke to the media about his interest on Thursday - the day before Celtic announced they had come to an agreement with the player.

"I've never spoken to Ronnie and, as far as I'm concerned, I won't either and that's the way it'll remain," McNamara told BBC Scotland.

"I think Ronnie has a way of doing things. He's been asked a question by the press.

"Obviously they've put him in a position about his interest in Gary Mackay-Steven and signing a pre-contract, which is fine, he can do that.

Ronny Deila spoke about Gary Mackay-Steven to the media on Thursday

"But in terms of taking him now, that's not within his remit to sign him just now. He's our player unless we decide otherwise."

Blades manager Nigel Clough tabled an improved offer of around £100,000 after watching Mackay-Steven score against Hamilton Academical on Monday.

However, it is understood that the winger was not keen on playing in England's League One and the Tannadice club have said it will take a minimum of £250,000 to prise the player from Tayside during January.

While Mackay-Steven said earlier this month that he expected to remain at Tannadice until the end of the season, Deila said: "He is a player we have been looking at for a long time. If we can do something now, we will do it, but everything has its price."

Mackay-Steven, who has earned one cap for Scotland, began his career with Ross County and had a spell with Liverpool before returning north to join Airdrie United.

The winger moved to Tannadice in 2011 and has scored 27 goals in 130 appearances for the Tayside club.

He has found the net five times in 22 appearances this season, helping United to third in the Scottish Premiership table, five points behind leaders Aberdeen.

On Wednesday, a United spokesman told BBC Scotland: "We do not need to sell him and if anyone wants him at this stage they will have to put up or shut up."