Heinze is apparently keen to become the first player to make the switch from Old Trafford to Anfield since Phil Chisnall in 1964 but Sir Alex Ferguson is equally determined to stop him.
At the centre of the wrangle is a letter, signed by Red Devils chief executive David Gill stating the figure United would be willing to sell Heinze for, a sum Liverpool have agreed to match.
Heinze contends United should now allow him to leave but Gill is adamant he informed the 29-year-old's agent verbally - before Liverpool made their bid - he was unwilling to deal with any of the club's major domestic rivals.
Papers from all sides are currently being examined by the Premier League, with Heinze keen for a ruling to be made before the August 31 transfer deadline.
And, while the Premier League are refusing to comment on the matter, it is understood they will examine more documentation in an effort to find a solution.