The German Football Association (DFB) are to look into Gerald Asamoah's claims he was racially abused by Borussia Dortmund goalkeeper Roman Weidenfeller.

The Schalke and Germany striker revealed on German television that he had been called a "black pig" by Weidenfeller, who had since apologised, but denied using those words.

"Words are always said in such a game, but when you hear things like that, it is very disappointing," Asamoah told WDR.

"You cannot say that. Weidenfeller apologised to me while the game was still being played and he regrets it, but I don't know why he cannot admit it afterwards.

"He should tell the truth."

Weidenfeller would not be drawn on whether he had used racially insulting words towards Asamoah during Saturday's 4-1 defeat.

Both he and Asamoah have been asked to provide a written statement to the DFB, who will also await the report of referee Knut Kircher before deciding whether to take any action.

The event overshadowed what had otherwise been a remarkably peaceful Revier derby.

Schalke got their revenge for losing to Dortmund at a crucial stage of last season, but there was no ramifications outside the Arena AufSchalke as local police forces spoke of a lower than usual rate of incidents.