Dortmund could withdraw its bid to become a host city at the 2024 European Championships because of an unclear financial situation, its mayor has warned.
Local outlet Reviersport quoted Ullrich Sierau as saying: "If the business model of the German FA (DFB) and UEFA is to let us pay and them cash in, then it's a bit lopsided."
Sierau said the DFB demands that candidate cities "support them in the best way at their own expense," adding that it could not accurately be estimated how high those costs might be.
Reviersport reported that the bill facing the city could hit €30 million, and Sierau said a decision on whether to withdraw the bid would be made at a council session on June 1.
Dortmund's Westfalenstadion, one of the great stadiums in European football, is reported to be part of the bid.
Earlier this month, the city of Kaiserslautern announced that it had withdrawn its bid because of "irresponsible financial risk."
Germany and Turkey will compete to host the 2024 tournament, as they are the only nations to declare an interest. UEFA's executive committee will make a decision in September 2018.
With Germany considered to be the favourite, 14 cities have so far announced that they will bid to stage games and have until June 12 to make their bids formal.