Reports claim that Manchester United are close to signing Carloz Tevez on a two-year loan deal with the Argentina striker likely to seal a move to Old Trafford in the next 24 hours.
But West Ham have now moved to stop the 23-year-old leaving Upton Park this summer by stating that he still has three years to run on his contract.
Magnusson expects Tevez, who is currently on international duty playing in the Copa America, to return to West Ham ahead of next season.
"Carlos Tevez is a registered West Ham United player, contracted to the club until June 2010," he said in a statement on the club's official website.
"There is no agreement with West Ham United for Carlos Tevez to leave the club and we expect him to return in time for next season's preparations.
"No decision on his future can be reached without the agreement of West Ham United."
Any deal which takes Tevez to Manchester United will be under scrutiny from the Premier League and West Ham are likely to be backed in their stance.
