Barry Robson tonight completed his dream move from Dundee United to Celtic.The 29-year-old midfielder agreed a three-and-a-half-year contract and passed a medical after agreeing personal terms for the move to Parkhead. Robson, who was United's captain, has hit 12 goals already this season, including seven in his last five appearances. Robson becomes Celtic's third signing of the week, following the deals bringing Japanese midfielder Koki Mizuno to Glasgow from JEF United and Greek striker Georgios Samaras on loan from Manchester City. Celtic's Jim O'Brien moves in the opposite direction, joining United on loan until the end of the season. Nottingham Forest were the first club to lodge a seven-figure offer for Robson but the Scotland squad player favoured a move to Celtic. Hoops boss Gordon Strachan made his move this morning, as Celtic followed up their interest with a firm bid. United manager Craig Levein confirmed he and chairman Eddie Thompson had wanted to keep Robson. Levein said: 'Both myself and the chairman would have preferred Barry to remain a Dundee United player, but he made it abundantly clear on a number of occasions that he wanted to move on. 'He felt that at his age, he had one last chance of a major contract and we couldn't persuade him otherwise. 'He's a fantastic player, greatly admired by the chairman and myself and we wish him well in his future career.' Celtic also bought Germany international defender Andreas Hinkel earlier in January, with the 25-year-old costing £1.9million from Sevilla. Robson is already a member of the Scotland squad and will hope his move to Celtic improves his chances of adding to his one international cap under new boss George Burley. His priority though will be to help Celtic win trophies, and Robson could play a key role for Strachan's team over the remainder of the season. He will challenge Massimo Donati and Scott Brown for a central midfield role, and the competition in places could bring the best out of all three as Celtic look to reel in Clydesdale Bank Premier League leaders Rangers, who currently have a four-point advantage at the top of the table. Robson will be unveiled by Celtic tomorrow, along with Mizuno who arrived in Glasgow today. Aberdeen-born Robson was an outstanding signing by United in 2003, costing just £50,000 from Inverness as Ian McCall brought him to Tannadice. Robson, who is predominantly a left-footed player, hit 36 goals in 165 appearances for United and Scotland recognition came last August when he came off the bench during the 1-0 victory over South Africa in a friendly at Pittodrie. O'Brien, 20, could be a direct replacement for Robson after accepting the chance to join United. He can play in midfield or in a more advanced role, and has a good eye for goal. Levein is ready to give him every chance at United, and Strachan will be pleased to see a fringe Hoops player handed experience in the SPL. Levein said: 'I'm delighted to add Jim O'Brien to the squad. 'He's proved he can score goals at every level and is highly regarded throughout the game. 'In fact, I tried to get him last year at this time but a deal had already been done to take him to Dunfermline. He can play wide right and in midfield and will strengthen the attacking options available to me.' Celtic were also on the verge of selling midfielder Jiri Jarosik to Russian side FC Krylya Sovetov. With Robson coming in, Jarosik was set to become surplus to requirements. Celtic confirmed they have also signed Middlesbrough striker Ben Hutchinson with immediate effect. The 20-year-old had previously agreed a pre-contract move which would have seen him arrive in the summer. However today he came through a medical in Glasgow and tied up a three-and-a-half-year deal, with the fee, as in Robson's case, so far undisclosed.