Real Madrid have conceded that it will be “impossible” to sign Cristiano Ronaldo this summer unless he demands a move, something that they still hope he may be prepared to do. Even in retreat, however, their president could not resist antagonising Manchester United yesterday, mocking Sir Alex Ferguson's comments about Spanish history.

Ramón Calderón, the Real president, infuriated United last month by suggesting that “nobody can prevent a player from moving because slavery was abolished a long time ago”, to which Ferguson responded by making reference to the Spanish club's well-known historical links with the despised regime of General Franco.

Carlos Queiroz, Ferguson's assistant, also sought out the history books, likening Real's relentless pursuit of Ronaldo to Spain's battle for the town of Olivença, on the disputed border with Portugal, and to its claims to Christopher Columbus, the Italian explorer.

Calderón suggested yesterday that United's fears of unlawful conduct by Real were misplaced, but he was also scornful of the comments by Ferguson and Queiroz. “They made references to Franco and to the Spanish occupation of Portugal,” Calderón said. “They didn't seem to me to be very well adapted.

“For now, Cristiano Ronaldo is an impossible signing. We can't do anything if the club who own him don't sell him. We would never [induce him to break his contract]. That is not the policy of Real Madrid with any club - and even less so with a club with which we have good relations, such as Manchester United.”

Even though his planned announcement about his future is yet to materialise, United are increasingly apprehensive about the Portugal forward. His mind seems to be set on playing for Real, but Barcelona will battle with their rivals for his signature if and when he decides to leave Old Trafford.

In particular, Ronaldo would be a priority for Barcelona next summer - assuming that he is not already in Madrid - as rival candidates for the club's presidency plan to launch their electoral campaigns on the back of bids to sign him.

Joan Laporta will stand for re-election, but Sandro Rosell, another candidate, believes that his links with Ronaldo - through Jorge Mendes, the player's agent, Luiz Felipe Scolari, the Portugal coach, and Nike, the sportswear company - could be significant.

United expect to see off competition from Arsenal, Everton and Liverpool within days to sign Aaron Ramsey, the highly rated Cardiff City teenager. Arsenal and Everton have also been given permission to discuss personal terms with the player, having had offers in the region of £5million accepted by Cardiff, but United are strong favourites to sign him, with the 17-year-old midfield player expected to travel to Old Trafford for talks either today or tomorrow.