Two top rival teams acknowledge that complex loopholes in the budget cap rules need to be closed by Formula 1's authorities.
The FIA last week played down rumours that, after Red Bull and Aston Martin were found in breach last year, two or three teams are once again at risk of penalties due to spending more than is allowed per season.
Red Bull's Dr Helmut Marko is now indicating that the rumours are true.
"Apparently, three teams could have exceeded the limit," he told motorsport-total.com.
Mercedes boss Toto Wolff revealed in Hungary last weekend that he has had "long chats" with the FIA's budget cap inspectors about compliance checks.
It follows the Paris-based federation's earlier issuing of a technical directive warning that a spotlight has now fallen on clever accounting between the F1 teams and their engineering subsidiaries.
Marko said: "Red Bull is developing the (2025) RB17 hypercar, and there are people who work partly here and partly there. How do you account for that?
"There are also people with us who no longer want to travel, who no longer want the pressure of Formula 1, so we can place them in such projects.
"And if they do work in Formula 1 for a few hours, then you have to calculate those hours."
"The whole issue of the cost ceiling is still too open to interpretation and too weak on the facts," the 80-year-old top Red Bull official added. "That's why there are still discussions going on.
"It's a topic that needs to be improved," said Marko.
Wolff agrees that it is currently "extremely difficult" for the budget cap inspectors to assess whether teams' non-Formula 1 staff are adding performance to the F1 cars.
"Many teams employ thousands of people involved in commercial and non-commercial projects," he noted.
"We have to improve that for the new regulations in 2026," said Wolff.
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