New Zealand rugby has expressed concern about players as young as 15 being targeted by overseas clubs.
In an interview with the Daily Telegraph the chief executive of New Zealand Rugby Steve Tew says the country's playing stocks are being threatened.
In the past year, the five New Zealand franchises have lost 17 players, including seven All Blacks, to European clubs including Aaron Cruden, Steve Luatua and Malakai Fekitoa as their Super Rugby season starts this week.
Many more are also set to depart, with England club Wasps announcing the signings of Lima Sopoaga and Brad Shields for next season.
Fellow All Blacks Liam Messam, Jerome Kaino and Charlie Ngatai are also sett o leaveheading for the exit door.
Tew is accustomed to high-profile players being targeted but told the Daily Telegraph that it was the targeting of school-age players that was setting alarm bells ringing.
"Clubs are increasingly talking to agents about players at a much younger age. Unfortunately it is getting younger and younger to a point we are going to have sit down to make sure we are not talking to young men before they are ready to make those type of decisions. It is teenagers, sometimes 15-year-olds, being approached about signing by clubs in both union and league. That's scary. We have to be very careful."
World Rugby has extended the residency qualification period for international players from three to five years effective from 2020, however Tew believes this may have caused clubs to target even younger players.
"With the five-year eligibility rule coming in that may or may not help," Tew said.
"We may see them target younger players even earlier and try to qualify them for the five years. What we are seeing at the moment is younger players being offered longer contracts. It is an ongoing conundrum without a straightforward solution in a free market. As bad as it is for New Zealand, it is a hell of a lot worse for Samoa, Fiji and Tonga.
"It is a concern to us, but it should also be a concern to those [foreign] unions too because we are seeing foreign players filling up a number of critical positions within teams and leagues. In the long term that cannot be good," he said.
Domestically, NZR have long been competing for talent with rugby league -- particularly in its largest city Auckland -- and were involved in a recent tug-of-war with rugby league's New Zealand Warriors over fullback Etene Nanai-Seturo.
The 18-year-old was selected for the All Blacks Sevens team for the Sydney leg of the World Sevens Series earlier this month despite having signed a five-year contract with the Warriors.
Nanai-Seturo signed the contract as a 15-year-old.
NZR reached a confidential agreement with the Warriors earlier this month for his release.