Schalke has apologised for its fans’ racist abuse of Borussia Dortmund youth player Youssoufa Moukoko during a match between the rival clubs’ under-19 sides on Sunday.

"Derby emotions aside, we completely condemn and oppose such insults,” Schalke said on Twitter.

In a tweet with the hashtag “NoToRacism,” the club said its supporter relations department “will take the necessary measures.”

The 15-year-old Moukoko, who is Black, will be eligible for Dortmund’s senior team when he turns 16 on Nov. 20. He scored a hat-trick in the under-19s’ 3-2 Ruhr derby win on Sunday. It was his third hat-trick in three competitive games.

Kicker magazine reported that some Schalke fans directed “nasty insults” at Moukoko after he scored his third goal from distance against their side in the 63rd minute.