Leeds signed the striker from RB Leipzig on a loan deal with an obligation to buy for a fee of €21m if they were promoted to the Premier League.
Augustin did little to impress Marcelo Bielsa and Leeds sent him back at the end of the original loan agreement, refusing to sign him permanently as they had not been promoted at the end of June.
Leeds have gone on to spend big on Rodrigo and Robin Koch, but RB Leipzig are insistent that Leeds are still legally obligated to sign the striker as per their agreement in January.
The Germans have taken note of Leeds’ spending in the window and stressed that the club are not living up to their word. Florian Scholz, the club’s commercial director, claimed that they are getting ready to take legal action against the newly-promoted Premier League side.
Scholz told German outlet Sportbuzzer: “The legal situation is clear.
“Leeds are currently spending a lot of money in the transfer market, but they are not living up to their contractual obligations.
“We are ready to take further steps.”
Leeds are in no mood to have Augustin back at Elland Road, but could still be forced to pay €21m for him and then try to sell him to another club.