The NRL salary cap auditor rejected the PNG Chiefs' initial offer for Canberra forward Hudson Young, judging it below his assessed market value.
NRL executive chairman Peter V'landys says the club must pay full market value and that no team will be allowed to manipulate the cap.
"It's unfair on Canberra if they offer $1.1 million and he goes for $700,000 to Papua New Guinea, that's all we're trying to stop," V'landys said.
"That's why I came out publicly on this one (Hudson Young) because I wanted to make it known that the salary cap will not be manipulated."
Players can make case-by-case submissions to revise their market value, but Young's management has not done so, V'landys said.
The November 1 player market opens in six days, and the Chiefs are preparing to offer tax-free contracts.
Young is the first star whose tax-free PNG offer has been rejected, but the Chiefs still need to fill 23 of their 30 roster spots before their 2028 NRL debut.
The issue has renewed concerns about salary cap fairness, since players could take home more from lower tax-free salaries than from offers in Australia or New Zealand.
All 18 NRL clubs are expected to watch the salary cap auditor closely in the coming weeks and months, according to the Canberra Times.