"We have tried to contact him and hope that nothing bad has happened".
Dembele, who has made no secret of his desire to play for Barcelona, may have been trying to break the deadlock with his no-show, Bild suggested. We don't know why.
Barcelona have been working on a deal to sign the 20-year-old since Neymar's departure to Paris Saint-Germain and the player has also been keen to move to the Nou Camp.More news: 9/11 victim's remains have been found almost 16 years later
Earlier this week, Dortmund chief executive Hans-Joachim Watzke said a fee of €100m for the player was "in every case, not enough" and the Bundesliga side's asking price is reported to lie closer to €135m.
"As there is no other offer from FC Barcelona to date, a transfer of the player to FC Barcelona is at present not more than likely".
"Ousmane Dembele was not in training today".More news: Venezuela says it has put down uprising at army base
Some media outlets have spoken about an agreement between Dembele and the Catalan team although Dortmund have not confirmed this.
Dortmund have also rejected bids from Arsenal and PSG for Dembele this summer.
Barca have always been linked with a move for the 20-year-old winger, but have acted on their interest after selling Neymar to Paris Saint-Germain for €222 million, with some reports stating Dembele has already agreed to the move.More news: He will need dialysis, says doctor
Borussia Dortmund bought Ousmane Dembele just last summer from Rennes, but it looks like they're going to have to offload the Frenchman already, with Barcelona heavily interested in the talented youngster.