Alex Ferguson has vowed Manchester United will not let Liverpool "get off" with any dishonourable conduct in the Gabriel Heinze affair.

Ferguson has revealed United chief executive David Gill is investigating what contact Liverpool had with Heinze over a proposed move to Anfield, which fell through earlier this week, triggering the defender's eventual transfer to Real Madrid.

Although Ferguson did not use the words "tapping up", when he was asked whether United felt that is what had happened, he replied: "We will see."

Chief among United's concerns is how solicitor Richard Green, who advises Liverpool, came to be acting for Heinze in his attempt to prove a letter - signed by Gill and stating a fee which would be acceptable for the player - was an agreement to sell.

A three-man Premier League tribunal rejected the claim on Tuesday but, with Liverpool supposedly having no direct involvement in the case, United want to know how Heinze secured Green's services given the 29-year-old still had two years of his United contract to run.

United's unhappiness with Liverpool has only increased following Rafael Benitez's outburst in which the coach, while stressing his amazement at the Premier League's ruling, effectively claimed United enjoyed preferential treatment, not just over Heinze but also in the drafting of fixtures and the "smooth" move of Carlos Tevez from West Ham compared to the deal which saw Javier Mascherano join Liverpool in January.

It was a rant which smacked of sour grapes and could yet land Benitez in hot water with the Premier League.

"What Rafa said is a bit churlish," declared Ferguson. "He obviously did not study the Premier League rules because he had no chance of winning the case.

"But we are looking at Liverpool's whole role in this. David Gill is working on it at the moment. We will get to the bottom of it and see what comes out because we are not letting them off with it.

"I am really disappointed with Rafa."

Aside from his suspicions about Liverpool and Benitez, Ferguson is also hugely critical of Heinze's agent, Roberto Rodriguez, who he claimed will benefit financially from the player ending his association with United.

Other than a brief nod of the head, Ferguson never had a proper chance to say goodbye to a player who made 83 appearances for United following his arrival from Paris St Germain in 2004.

"I have no axe to grind with Gaby, none at all," said Ferguson. "When he played for us, he was a warrior. I have not had a chat with him. I said hello at the tribunal but obviously it was very difficult because he was there with three barristers, two agents and an interpreter and some Spanish lawyers."

Meanwhile, David Beckham's draining transatlantic schedule is beginning to concern his employers at Los Angeles Galaxy.

The former England captain drew a blank, along with his team-mates, in Galaxy's 3-0 Major League Soccer derby defeat against Chivas USA on America's west coast on Thursday, less than 30 hours after he had finished playing against Germany around 5,500 miles away at Wembley.

Galaxy general manager Alexei Lalas told BBC Sport: "We have a vested interest in this player and we have spent a tremendous amount of money to retain his services.

"We want to make sure we get our money's worth and that he is healthy and both physically and mentally ready to go when he plays for the Galaxy."

Lalas hinted Galaxy will not be afraid to try to stop Beckham burning himself out with avoidable air miles.