Manchester City have confirmed they have written to the FA voicing their concerns about how the FA Cup defeat at Bramall Lane was handled.
The club believe that referee Alan Wiley and his team should not only have stopped play but instructed Sheffield United staff and stewards to remove the balloons.
City claim that the officials' failure to do so had a direct bearing on the first goal being scored in the tie, which ended in a narrow 2-1 victory for the Coca-Cola Championship side.