Internazionale will confirm Gareth Bale's growing reputation as the most sought-after player in world football with a £40m bid in the summer, the most that has ever been offered for a player of his age and experience.

The move, if successful, would shatter the transfer record for a British player and propel Bale to an elite within the game in which perhaps only Wayne Rooney, of home-produced contemporaries, could count himself.

That £40m sum could rise higher as the Italian champions' move is expected to spark an immediate bidding war with Real Madrid, where José Mourinho has also made the Tottenham Hotspur winger his principal summer target.

Such a move would place Bale, still only 21, among a gilded elite of expensive footballers. Only four players have ever moved for more – Ronaldo (Manchester United to Real for £80m), Zlatan Ibrahimovic (Inter to Barcelona for £56.5m), Kaká (Milan to Real for £56m), Zinedine Zidane (Juventus to Real for £45m) – and all had made significantly more impact on the European stage than Bale, who 12 months ago was just cementing his place in the Tottenham first XI. The transfer record for a British player remains the £29m Manchester United paid Leeds United for Rio Ferdinand in 2002.

Massimo Moratti, the Inter president, has placed Bale at the top of his wish-list after being smitten by the manner in which he performed against his team at the Champions League group stage. Bale scored a hat-trick in Tottenham's 4-3 defeat at San Siro, a display that had Moratti purring, and he was also outstanding in the White Hart Lane return, which his team won 3-1. Both games were notable for Bale's dismantling of Maicon, the Brazil right-back previously considered by many the world's strongest in his position.

Real, meanwhile, made inquiries about Bale last summer and they have monitored him closely as the season has progressed. Mourinho, the manager, admires him greatly while it is often said that Real is the one club players find impossible to turn down. They continue to wait in the background, having asked to be kept up-to-date with Bale's situation and they would be ready to rival the bid from Inter.

Tottenham have consistently stated that Bale is not for sale but the money set to be put in front of them will test the resolve of the chairman Daniel Levy, who has the reputation of a hard-headed and savvy businessman. With either a move to the Olympic stadium or a redevelopment of White Hart Lane in the offing, Tottenham will find a ready home for the money.

Bale has lit up Tottenham's debut season in the Champions League, with his performance at San Siro on 20 October being the highlight. Moratti was in raptures after the game, not only about Bale's pace and technique but his character. He was impressed that the Welshman had carried the fight for Tottenham almost single-handedly but he remained wedded to the team ethic.

The reputation of Maicon appeared to be in tatters after his meetings with Bale. At White Hart Lane, the crowd chanted "Taxi for Maicon" to compound his humiliation. But Moratti continues to rate Maicon as one of the best in the world and it registered with him that Bale had not destroyed just anybody.

Moratti has since sacked Rafael Benítez as the manager and replaced with him with Leonardo, the Brazilian, who would lean towards the Latin American market for new signings. But Moratti has the final word and he has resolved to make Bale his big summer deal. Inter would more than treble Bale's wages, making him easily the wealthiest 21-year-old in football.

Bale will be confronted by difficult questions when the bids come in. He is happy and settled at Tottenham, where he is popular, and he enjoys his football under the manager Harry Redknapp. Would the summer be the right time to move or should he wait, perhaps to play another season of Champions League football at White Hart Lane?

Moreover, how would he take to life abroad? Bale is, at heart, a humble boy from Cardiff. Levy would be loth to sell to an English rival, despite there being plenty of interest from the country's leading clubs.

It would be unwise of Tottenham not to guard against the possibility of Bale being prised away and the signing of Steven Pienaar from Everton last week has been interpreted in some quarters as making a provision for his departure. Although a different type of player to Bale and one who can play in a few positions, Pienaar is, fundamentally, a left-sided midfielder.

Tottenham also have an interest in the Aston Villa winger Ashley Young and they scratched the back of the Midlands club earlier in the month when they allowed the highly-rated 20-year-old full-back Kyle Walker to join them on loan. They could be expected to bid for Young if Bale were to leave.

Redknapp does not want to lose Niko Kranjcar, who was supplanted on the left by Bale's emergence in 2010. Kranjcar has made it clear that he cannot tolerate his lack of playing time but a temporary solution to suit all parties might be a loan move until the end of the season. There is no shortage of takers for the Croat.

There is little doubt that Tottenham's hopes of keeping Bale would reduce dramatically if they failed to qualify for next season's Champions League. The 21-year-old has revelled in the challenge that Europe's elite competition provides and he now has the taste for it every season.