Manchester City made a prohibited payment of 200,000 pounds to the agent of Jadon Sancho, Emeka Obasi, when the player was 14, according to claims in Der Spiegel.
Sancho, who has since left City for Borussia Dortmund, was at Watford in 2015 when the illegal payment was supposedly made to his agent.
It's a payment which the Football Association has banned in regards to players who have not yet turned 16 years old -- the age when they are allowed to have an official agent.
"The attempt to damage our reputation is organised and clear," City said in a short statement responding to the claim.
"We will not be providing any comment on out-of-context materials purported to have been hacked or stolen from City Football Group and Manchester City personnel and associated people."
Der Spiegel alleges City made the payment to Obasi as part of a scouting contract when it was in fact a sweetner to bring Sancho to the club.