Dimitar Berbatov has been Manchester United's principal transfer target for more than a year and yesterday their dogged pursuit of the Bulgaria forward led to a formal complaint being lodged with the Premier League by Tottenham Hotspur.

Sir Alex Ferguson has made it his priority to sign Berbatov after failing with a £24 million offer towards the end of last year's transfer window. The United manager raised the stakes on Thursday when he said that United had “made a bid for one player who would enhance us a great deal”. He did not name Berbatov, but he did not have to.

For all United's riches in attack, they lack a genuine No9. Berbatov, at 6ft 2in, would provide Ferguson with height and a clinical finisher in the box. He would most likely be deployed at the head of a three-pronged attack, alongside Wayne Rooney and Cristiano Ronaldo.

Berbatov spent much of last season in a state of discontent after his request to leave the North London club was turned down. At the end of last season, the 27-year-old said goodbye to several club staff, believing that he would secure a move to Old Trafford, AC Milan or Barcelona by the start of pre-season training.

Privately, Tottenham acknowledge that they cannot keep him, but while a formal complaint by Daniel Levy, their chairman, to the League about United's pursuit of the player will be applauded by some, others will consider it a negotiating tactic to ensure that they obtain a fee close to their £32 million valuation.

“[There has been] a series of events, dating back to last summer, which have shown Manchester United to be in breach of Premier League rules,” Levy said. Middlesbrough, however, might point out that Tottenham have made a similar, if less public, pursuit of Stewart Downing, their winger, in the past three years.

Liverpool's bid to sign Robbie Keane, the vice-captain, has come as more of a surprise to Tottenham, who are upset that there have been leaks to the media from Anfield. Levy was angered when Rafael Benítez, the Liverpool manager, admitted that he was trying to sign Keane and talked about what the Ireland forward could offer his side, although there is nothing unusual in the Spaniard expressing his opinion on a player.

Benítez said nine days ago: “Keane is also one of the names we are interested in, and we are still working on other possible situations. There has been some contact [over Keane] but we will have to see how things progress. Keane is clearly a player that has game intelligence and we are looking for players who can fit into our systems and improve the team.” Liverpool maintain their hope of finalising a deal for Keane, worth up to £18 million, this week.

“Our subsequent position has been severely compromised by both clubs making their intentions widely known and indeed making contact with the players and their agents, without the club's permission,” Levy said in a statement last night.

“I have absolutely no wish to sell either player and to date we have not accepted any offer for either. However, when a player's head is turned and their commitment is absent, particularly when they occupy key positions such as that of striker, they become a negative influence in a team dressing-room.

“This is the situation we now have with both Dimitar and Robbie having made it clear that they wish to leave for Manchester and Liverpool respectively.”

Ferguson on Real Madrid

“You get used to Madrid's performances on these things. Ronaldo has four years left on his contract and then Calderón makes this great statement that slavery has been abolished. Did they tell Franco that? Jesus Christ. Madrid have no moral issues at all. They think they can ride roughshod over everyone but they won't do it with us.”

Levy on Ferguson

“This is a blatant example of sheer arrogance and interference with one of our players. It is also probably one of the worst offences by any manager in the Premier League to date and is unbelievably hypocritical given his recent comments in respect of Cristiano Ronaldo and Real Madrid.”