Players are on the move because of the money sloshing around the northern hemisphere but World Rugby is pondering change as concerns grow over the game’s integrity at international level

World Rugby is considering a crackdown on country clubs. The lure of French rugby has become so strong in recent years that Toulon have come to resemble a World XV, Premiership sides will be allowed a second marquee player from next season – ahead of an accelerated rise in the salary cap – and sides in the Pro12 are looking to join the spree.

World Rugby, as the former International Rugby Board is now known, is stirring itself because of the impact the flood of players from south to north will potentially have on the international game. Players used to come to Europe or Japan in the twilight of their careers to provide themselves with a pension: now they are being attracted at a far younger age because of the opportunity to set themselves up, if not for life, well into retirement: Charles Piutau, the New Zealand wing, will join Ulster in summer 2016 on a deal worth a reported £500,000 a year.

He will then be 24 with his best years ahead of him. He will not be considered by the All Blacks because of the New Zealand Rugby Union’s policy of only picking players who play for one of its five Super 15 franchises, but he could return before the 2019 World Cup if his two-year contract with Ulster is not extended.

Piutau’s value to Ulster is enhanced because he will be available all season and, having been capped by New Zealand, he would not be available to Ireland after three years. There is nothing World Rugby can do to prevent market forces from dictating player movement, but it does have the power to make it harder for countries to behave like clubs by tightening up the regulations on international eligibility.

A player’s national allegiance is set once he plays for a union in a Test match, for the second team or in a major Sevens event; there is no going back. For those who are not tied, the three-year residency rule provides the opportunity to play for a foreign country. French clubs have been active for a few years in attracting players from abroad at college age so that, when they have finished their education, they are qualified to play for France.

It is not particularly that clubs in the Top 14 want their players to be capped by Les Bleus but more an acknowledgement that players, naturally competitive and driven by ambition, aspire to play at the top. Toulon, for all their high salaries and array of talent, cannot provide that. The World Cup final at Twickenham later this year will be a considerably bigger event than the Champions Cup final staged there last weekend. Better to have players in the France set-up than leaving every summer and autumn to play for the likes of Fiji.

“There is a concentration of club wealth in the northern hemisphere, there’s no question that the salaries are very high in France and in England and it’s very tempting for players to ply their trade in the northern hemisphere,” said Brett Gosper, the World Rugby chief executive. “Each union in the southern hemisphere must find ways so that it’s attractive still for their players to remain where they are, playing in Sanzar competitions, playing with the union they’ve grown up with and so on. The residency law was looked at a few years ago and it was determined that it seemed to be right for that particular time three or four years ago.”

One reason for that was that the rule suited unions in the south. Australia and New Zealand were able to attract players from the Pacific islands, but the gain from that is now offset by the loss of the likes of Piutau and Colin Slade long before their bus pass date. The potential denuding of New Zealand, not just the No1 ranked country in the world but the game’s biggest brand, has forced a rethink.

“Bernard Lapasset [the World Rugby chairman] has indicated we may have to look at whether the three-year residency rule is enough to ensure the integrity of the international game,” said Gosper. “You want to preserve the specialness of it and, while clubs sides are gathering top international stars from all around the world, there is a feeling that some steps need to be taken to ensure that the profile of the national team has an integrity. When the residency rule was set, there was not quite the same flow of players internationally through Europe and Japan.”

Any change would not happen quickly. A working group would need to be set up to report back to World Rugby’s executive who would then make a recommendation to the council. That would take more than a year and the council is made up of unions who would be bound by self-interest: England, France, Wales, Ireland, Scotland and Italy have all capped players since the last World Cup who qualified on residency: the rule has suited north and south.

World Rugby has been moved to investigate because its own organisation would be threatened by a diminution of the international game: it makes its money through World Cup profits every four years. The draw of New Zealand, South Africa and Australia every European autumn is that they are hard to beat, and in the case of the first two, always have been. Take away that aura and the profits of every union in the Six Nations will shrivel, something that would ultimately impact on clubs.

Increasing the residency rule would be one deterrent, but reviewing relation 9, which governs the release of players to national sides, would be another. At the moment, it covers laid-down periods for training and playing. Making it greyer would decrease the value of having current international players while the way the proceeds from Test rugby are divided should also be looked at.

New Zealand are a bigger draw in Europe than any of the respective Six Nations are Down Under, but the financial split from matches is heavily in Europe’s favour. If that changed, it would have far more of an impact on player movement from the major southern hemisphere nations than reform of the residency rule.

• This is an extract taken from The Breakdown, the Guardian’s weekly rugby union email. To subscribe visit this page, find ‘The Breakdown’ and follow the instructions.