Carlos Queiroz, the Manchester United assistant manager, launched an astonishing attack on Real Madrid yesterday with a series of historical barbs as the row about the future of Cristiano Ronaldo rumbled on.

In the latest chapter of the saga, Queiroz accused Real, the club he used to manage, of attempting to “naturalise” Ronaldo, his fellow Portuguese, and suggested that the Spanish champions' pursuit of the United forward was part of a wider plan to undermine Portugal's preparations for the European Championship finals next month.

Bernd Schuster, the Real coach, outraged United this week by claiming that a deal was all but in place to sign Ronaldo this summer, prompting Queiroz to draw comparisons between the player and Christopher Columbus, the explorer, whom both Portugal and Spain claim as their own. He also alluded to Olivença, a town on the disputed border between the countries. “Cristiano Ronaldo will never be Spanish,” Queiroz said. “As they will never take Olivença again. They [the Spanish] already did the same with Christopher Columbus, and it now seems they want to naturalise Cristiano Ronaldo.”

Queiroz reiterated that United's desire to keep Ronaldo, who has four years left on his contract at Old Trafford, would not wane with an ironic reference to the 60-year Philippine Dynasty, when Portugal was ruled by three Spanish kings until it won independence in 1640. He also claimed that Real were merely trying to disrupt his country's plans for Euro 2008 for the benefit of the Spanish national team.

“Have they [Spain] already forgotten what we [Portugal] did to them in the past?” Queiroz said. “We will never lose our patience. It's [Real's courting of Ronaldo] being done in a manner to distract the Portugal team, at the height of their preparations for the European Championships,” Queiroz said. “I am convinced that despite pressure from the Spanish sporting press he [Ronaldo] will not accept to change his nationality.”

Having warned Real on Tuesday that they would report the club to Fifa, the sport's world governing body, if their public campaign to lure Ronaldo to the Bernabéu did not cease, United are understood to be dismayed by Queiroz's comments at a time when they hoped to draw a line under the saga.

Ramón Calderón, the outspoken Real president, met with three of the Spanish club's directors on Monday, when he was told to stop talking about Ronaldo, but Queiroz's remarks are likely to lead only to an escalation in the unseemly war of words.

Queiroz and Sir Alex Ferguson, the United manager, have been cleared of charges of improper conduct by the FA relating to comments about the match officials in the wake of the club's FA Cup quarter-final defeat by Portsmouth in March.

Ferguson claimed that Keith Hackett, the general manager of the Professional Game Match Officials, the referee's governing body, was “not doing his job properly” after Martin Atkinson, who officiated United's 1-0 defeat at Old Trafford, was not punished for what the United manager perceived to be a number of poor decisions.

Queiroz, meanwhile, had accused Atkinson of being “a disgrace” for denying Cristiano Ronaldo a penalty appeal only for Portsmouth to be awarded a spot-kick later in the game.

United will officially unveil a statue of George Best, Sir Bobby Charlton and Denis Law outside Old Trafford today before a special dinner at the stadium in the evening to mark the 40th anniversary of United's first European Cup win.

Meanwhile, Patrice Evra, the France left back, hinted yesterday that he could leave Old Trafford unless the club doubles his £35,000-a-week wages amid interest from AC Milan.

Evra is in a strong bargaining position as United would be loath to lose the player for nothing when his contract expires next summer, but with more talks due to be held with the Frenchman's representatives today, the English and European champions are confident that an agreement over a new deal will be reached.