The Champions League runners-up had previously ruled out the sale of the Poland international to rivals Bayern Munich, and are now adamant he will not be sold abroad either
The Poland international is keen to leave BVB ahead of the 2013-14 campaign, and made clear his desire to follow Mario Gotze to Bayern Munich before his contract expires in June 2014.
|2/1||Robert Lewandowski is 2/1 with BetVictor to join Manchester United
The striker has since been linked with a host of Premier League sides, including Manchester United and Chelsea, but Dortmund have now made it clear that they will not sanction a move abroad.
"Robert will now definitively play for Borussia Dortmund next season. We need clarity in order to plan for the future," Watzke was quoted as saying by Suddeutsche Zeitung.
Sporting director Michael Zorc, meanwhile, has also confirmed that Lewandowski is going nowhere as they are set to kick off their preparations for the new season.
"We will start our pre-season in two weeks time. We wanted to have clarity on this matter," added Zorc.
Dortmund's decision not to sell Lewandowski this summer means that the 24-year-old is likely to leave the club on a free transfer next year.
Bayern Munich have reportedly already told the striker's agent, Cezary Kucharski, that they remain interested in Lewandowski and will sign him in 2014 if Dortmund don't budge this summer.