Borussia Dortmund may be forced to do without Armenian midfield star Henrikh Mkhitaryan for October's Europa League clash in Azerbaijan because of a diplomatic dispute, according to media reports.

Dortmund play Qabala away in Baku, Azerbaijan, on October 22 and German daily Bild claim Mkhitaryan would be denied an entry visa by Azerbaijani authorities.

There are no diplomatic relations between bitter neighbours Azerbaijan and Armenia, who have twice been at war in the last century.

Given his impressive form with eight goals in their seven wins so far this season, Dortmund are banking on Mkhitaryan, who has won 52 caps for Armenia, not being denied the chance to play in Azerbaijan.

"We hope this does not happen. Henrikh is a super important player for us with his brilliant performances in recent weeks," Dortmund spokesman Sascha Fligge told German broadcaster Sport1.

Azerbaijani website azerisport.com claims Mkhitaryan would be arrested on arrival in Baku because of an illegal visit he made to the Nagorno-Karabakh region in 2011.

The area is southwestern Azerbaijan is at the heart of the last war between the countries from 1988 to 1994.