Kylian Mbappe remains at the centre of a disagreement between French and Spanish footballing bodies after snubbing Real Madrid to stay at Paris Saint-Germain.
Mbappe, long linked with Madrid, announced last week he would be signing a new contract in Paris rather than joining the Champions League finalists as a free agent.
LaLiga chief Javier Tebas swiftly responded to the news by claiming it to be "an insult to football".
Those comments have unsurprisingly prompted replies from France, firstly from LFP president Vincent Labrune, whose letter to Tebas was reported on Thursday.
Labrune questioned "your latest attacks against Ligue 1 and one of our clubs", believing his counterpart's behaviour to be "completely inappropriate".
And that is a view shared by the UNFP, the French players' union, which released a statement also directed at Tebas later on Thursday.
"We can hear and understand the disappointment of people from Madrid and their compatriots, even knowing, especially in the world of football, that you don't win every time and that it is possible to say 'no' to Real Madrid, even for a third time," said the body on its website.
"But demonstrating to the point of incomprehension does not justify disrespecting the player, his club and all of French football in this way, unless we call into question the freedom for a footballer to sign a contract with the club of his choice?
"The arrogance of the remarks made is shocking and there is no need here to reply to our Spanish friends that they have hardly any lessons to give to French football in terms of financial management, protectionism and equality...
"Once again, the most enraged is Javier Tebas who, when it comes to PSG, forgets to turn his tongue in his mouth seven times before speaking.
"And his offensive, hateful remarks, without restraint or foundation, bring shame and discredit to him, especially with regard to his position.
"In the heart of the 70s, Jeannette sang 'Porque te vas?' ['Why must you leave?']. But Kylian Mbappe will not leave, no offence to the president of the Spanish league...
"So 'Porque Tebas?' asks the UNFP..."