Borussia Dortmund chief executive Hans-Joachim Watzke has accused AC Milan of lacking respect in their pursuit of Pierre-Emerick Aubameyang.

Aubameyang, the Bundesliga's top scorer in 2016-17, has been linked to Milan, Chelsea and the Chinese Super League at various stages of the close season, but Dortmund sporting director Michael Zorc told reporters on Tuesday that an unspecified deadline for the Gabon star to secure a move away from Signal Iduna Park had passed.

Watzke insists Aubameyang has been kept in the loop throughout and that there is no problem between Dortmund and their 28-year-old prized asset.

"We were in continuous negotiations with his agent and therefore with him as well. This was an open communication between us all the time," Watzke told reporters, explaining Dortmund had to defend their own interests.

"We had a meeting earlier. There is no dissent and I think we came towards Auba quite a lot because of his achievements and because he is an outstanding person."

Watzke's Milan counterpart Marco Fassone openely named Aubameyang as a target over the weekend – a move that has not gone down well in Dortmund.

"Sometimes Borussia Dortmund have to plan strategies," Watzke said. "It can't be that managers of other clubs just say, 'Oh well we would like to have this kind of player'.

"Those conditions, seen from AC Milan, show a lack of respect."

Aubameyang scored twice against Milan in a 3-1 win in Guangzhou on Tuesday as part of the International Champions Cup.

"Obviously he had flirted with the idea of doing something else, which is correct, but I think that he is happy with us, which you saw at the AC Milan game," Watzke added.

"He feels good within the team and within the club. We feel good with him being part of the club. So there are no problems."