United probe - Premier League to investigate the champions-elect

Sir Alex Ferguson's team beat derby rivals Manchester City 1-0 yesterday to go eight points clear at the top and they will clinch the title if Chelsea fail to win at Arsenal today.

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But United face seeing a season of triumph descend into chaos. In the worst-case scenario, they could have points deducted if they are found guilty of breaking the same Premier League rules under which West Ham were massively fined last week.

Howard,the 28-year-old American, had been on loan at Everton since last May and, under Premier League rules, was not allowed to play against United for the duration of the loan.

It was announced in February that the move was to become a permanent transfer. But it is understood that Everton agreed not to play Howard against United this season, and when the two sides met at Goodison a week ago, the American's place was taken by second choice goalkeeper Iain Turner. The 22- year-old made a crucial error, allowing United to start the fightback which led to their 4-2 victory.

The Premier League are now set to investigate whether an agreement over Howard's availability existed and, if so, whether it breached the same rules which saw West Ham suffer a £5.5m fine over the transfers to Upton Park of Javier Mascherano and Carlos Tevez.

Those rules, U18 and B13, ban clubs from entering into agreements which allow a third party to influence another club's selection policy and dictate that clubs must act with good faith towards each other and the Premier League.

The League have confirmed to The Mail on Sunday that no such agreement regarding Howard was included in the transfer documents lodged with them by the clubs and that if United had requested it through official channels, they would have been refused.

A Premier League spokesman said: "There is no such clause in the transfer contracts of the player and we are contacting the clubs to try to clarify the situation."

Documents lodged with the Premier League when the transfer was agreed between the clubs make it clear that the permanent deal ran from February and that it was no longer a loan.

Reports at the time suggested the permanent deal would begin in June and the loan would continue until the end of the season.

Both clubs declined to comment on the issue last night.

But Everton will be questioned by Premier League secretary Mike Foster this week after their manager, David Moyes, appeared to confirm that there was an agreement between the clubs when he explained before the game against United why Turner was playing.

Moyes was reported as saying: "While Tim Howard was on loan he would not have been able to play against his parent club, United.

"Although we have now signed him ourselves, United wanted the loan clause to remain in operation. It was partly the reason we were able to tie up the deal for next season as early as we did. We have abided by their wishes."

United, managed by Sir Alex Ferguson, and Everton will be given a chance to explain the circumstances of Howard's transfer and his availability for his new club.

It is understood that Everton will claim a gentlemen's agreement' existed over Howard's availability and they were at liberty to pick him against United if they chose to. But such an argument may not satisfy the Premier League.

Premier League sources say that last season Birmingham attempted to insert a clause into a transfer deal forbidding Robbie Savage playing against them for his new club, Blackburn Rovers.

Birmingham were refused permission to do so.

West Ham were fined a total of £5.5m because they had allowed offshore companies to retain influence over Mascherano and Tevez.

The Premier League commission ruled that this represented a clear breach of rule U18.

West Ham were also found to have breached rule B13, stipulating that clubs must act in good faith, and the club's former chief executive, Paul Aldridge, was accused of telling the Premier League a direct lie' when asked about the agreements over the players.