Among the signatories were Agustin Pichot, Gonzalo Longo, Felipe Contepomi, Mario Ledesma, Ignacio Corleto, Omar Hasan, Jose Maria Nunez Piossek, Hernan Senillosa, Martin Schusterman, Gonzalo Tiesi, Rimas Alvarez, Pablo and Santiago Gomez Cora, Ignacio Fernandez Lobbe, Pablo Henn and Martin Durand.

Riesler told Ole newspaper: “The letter hurt me.”

The 53 have now been joined by six more players: Federico Serra, Hocario Agulla, Juan Gomez, Horacio San Martin, Gaston De Robertis and Jaime Arocena.

Top members of Marcelo Loffreda’s current Pumas squad met representatives from the UAR in Europe last week but their demands were totally rejected by the Union.

“I took notice of players’ demands on Saturday. We sent emails to them to invite them to talk, but…”

Riesler said before dismissing the players’ claims that the UAR had shown them a a lack of respect.

“I don’t think it was like that. We put it clear. I don’t want to talk much more about this.”

As well as being unhappy over the union’s treatment of home-based players, non-payment of match fees and expenses, the players want the UAR to upgrade the facilities in Argentina to the level of other Test-playing nations.

The UAR are in financial crisis after losing a court case to Jose Bustamante, a player who was rendered quadriplegic when injured in a domestic match.

As a result, players have been told they will not be reimbursed for expenses, meaning European-based players have to pay their own costs to return to Argentina to play next month’s Tests against Wales and New Zealand.

If the deadlock is not broken in the next four weeks, head coach Marcelo Loffreda – who may step down in any case – might be forced to pick a novice XV for the June 17 Test with Wales and June 24 clash with the All Blacks.