PSV sporting director Marcel Brands has expressed his outrage after Sporting Lisbon announced Zakaria Labyad as their latest signing on Monday.
The Eredivisie outfit are currently locked in a contractual dispute with the midfielder, who believes that he is a free agent.
However, PSV insist that earlier this year they triggered an option to extend the Morocco international's deal until 2014 and are therefore furious that Sporting have claimed Labyad as their player on their official website.
"This is disrespectful, both from Labyad and Sporting," he said told Eindhovens Dagblad.
PSV also intend to fine the 19-year-old, who also failed to turn up for the first day of pre-season training at the weekend.
"Why am I not at De Herdgang?" Labyad wrote on his Twitter account. "Because I just got out of bed."
The teenager, who was born in Utrecht but has been capped once by Morocco, is a product of PSV's youth system.