Record 24-time French Top 14 champions Toulouse were handed a two-point penalty by the league's organisers on Monday for 2022's transfer of Melvyn Jaminet from Perpignan.
The French national league (LNR) investigated the 450,000 euros ($529,121) move due to a breach of the Top 14 salary cap.
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Last week, Toulouse faced a disciplinary hearing by the LNR, who run the Top 14 and second-tier Pro D2.
Les Rouge et Noir drop down to second place in the table following the decision, with Pau replacing them in first.
"The disciplinary committee has imposed the following on Toulouse," the LNR said on Monday.
"A two-point deduction in the Top 14 table for the current season and a two-point penalty suspended. And also a fine of 45,000 euros, of which 15,000 euros are suspended."
The Jaminet saga has hung over Toulouse for months with the club having paid 1.3 million euros to the LNR as a settlement in March. The full-back has since left Toulouse, joining Toulon in 2023.
The club have seven days to appeal the decision.
"Toulouse takes note of the decision issued by the French national league," the Top 14 holders told AFP.
"The rulings handed down come at the end of a procedure whose methods have profoundly affected our image, and we regret this.
"Committed to our values of transparency and responsibility, Toulouse will, in the coming days and together with our advisers, assess the opportunity to appeal in order to uphold our rights," they added.
In the second-tier, Dax were deducted nine points for financial irregularities by the LNR.
