Gary Mackay-Steven will not be allowed to leave Dundee United during the January transfer window for anything less than £250,000, Herald Sport understands.

It was confirmed on Tuesday night that Celtic had opened a dialogue with the 24-year-old winger, ostensibly with a view to taking him on a Bosman transfer when his contract expires this summer, while League One side Sheffield United have fallen way short of that valuation with the two bids they have so far submitted for the player.

While a contract extension for the player remains on the table, he has made no secret of his desire to have move on again this summer, most likely to fulfil a long-held ambition to have another crack at football south of the border after a couple years in Liverpool's youth ranks as a kid.

Derby County, Blackburn Rovers and Huddersfield Town have all also been credited in the past with an interest in the Thurso-born player, now a fully fledged Scotland international. While United may be tempted to cash in on the player who was signed from Airdrie United by Peter Houston, the club is in rude financial health and there are no shortage of potential spin-offs to aim for in the latter half of the season.

With echoes of the transfer of Willo Flood in January 2009, Mackay-Steven could help United book their place in the League Cup final, potentially against Celtic, with a semi-final victory against Aberdeen on the last day of the month, while funds from any potential sale could be negated by a loss of prize money if it resulted in the drop of a couple of league placings.

Meanwhile, manager Jackie McNamara's pursuit of January signings continues apace with the club reportedly closing in on former Motherwell striker Henri Anier.

The Estonian, who scored nine goals in 40 appearances for the Lanarkshire side, initially on loan from FK Viking, moved to German second-tier side Erzgebirge Aue in June but could arrive to bolster the Tannadice club's attacking options for the second part of the season.

McNamara, who paid £50,000 to capture Simon Murray from Arbroath earlier in the window, was also linked yesterday with a move for Partick Thistle full back Stephen O'Donnell.