Borussia Dortmund striker Pierre-Emerick Aubameyang has insisted that he "cannot understand" why he has been punished by the German club.

The 28-year-old has been dropped from the squad to face Stuttgart on Friday evening due to disciplinary reasons, thought to relate to a trip to Barcelona during the international break.

Separate reports in the German press suggest that Aubameyang has been suspended due to a lack of time keeping in training, but the Gabon international - linked with summer moves to Chelsea, Manchester City and Paris Saint-Germain - claims that he has done nothing wrong.

Aubameyang, also penalised by Dortmund last year for an unsanctioned trip to Italy, told Bild: "I didn't turn up late for training. After my trip to Milan I could understand my suspension because I ignored an announcement that time. This time I really can't understand it."

Dortmund have failed to win any of their last three games in all competitions, seeing them drop from first to third in the Bundesliga and all but out of last-16 contention in the Champions League.