Bayern chairman Karl-Heinz Rummenigge recently told various German media that Reus has a buyout clause in his contract with Dortmund, which runs out in 2017. Rummenigge has said the player could leave Dortmund next year for a set fee of 25 million euros ($33.46 million), about half of his estimated market value.
"Borussia Dortmund is noting with a certain anger that Karl-Heinz Rummenigge is using the media every three days to disclose internal affairs of Borussia Dortmund,"' chief executive Hans-Joachim Watzke said in a statement posted on Dortmund's home page.
Watzke said it was clear the intention behind Rummenigge's moves and that the Bayern chairman's disclosures will ''damage the already tense relations'' between the two Bundesliga giants.
Bayern exploited such clauses to lure Mario Goetze from Dortmund one year ago and then signed striker Robert Lewandowski when his contract with Dortmund expired at the end of the season, after pursuing the Poland striker for a year.
Reus missed the World Cup because of a knee injury suffered in the final warm-up match one day before the eventual title-winner Germany departed for Brazil. He is considered one of Germany's top forwards.
Reacting to Rummenigge's statements, Reus said his priority was to get healthy for the start of the new Bundesliga season in two weeks.
Reus spurned Bayern and decided to sign for Dortmund when he left Borussia Moenchengladbach in 2012, also using a buyout clause.