Marseille president Vincent Labrune has warned Ligue 2 champions AS Monaco that they will not be welcomed into the French top flight unless they comply with strict new laws regarding taxes.
The French Football League's (LFP) Administrative Council handed down a ruling requesting all professional clubs must be based in France for tax purposes, which would significantly increase Monaco's wage bill.
At present, the club's foreign players avoid paying income tax, but the LFP have voted to exclude Monaco from next season's competition unless they relocate their offices to France.
Labrune insists there is no defence for Monaco in the matter and has pushed for greater equality in Ligue 1.
"Next year, we will seek as usual to consolidate our position against increased competition with the arrival of a foreign club in Ligue 1," he said. "This is not a fight. Monaco is welcome to Ligue 1, but the LFP, our position is quite simple.
"I say yes to AS Monaco being in Ligue 1, but they must be in compliance with our legal and ethical rules as they have been defined.
"(Marseille) must try to consolidate our place on the podium without the means of the Russians at Monaco (owned by billionaire Dmitry Rybolovlev) or the Qataris of PSG and without being able to spend madly.
"We will try strengthening the team gradually year on year to qualify each season for the Champions League and to become competitive on the European stage."