"We are talking about nearly €3 ($3.8) per share," Flowers told the German daily Frankfurter Allgemeine Zeitung.
On Thursday, the shares traded for €1.65, way below the €22.50 paid by Flowers when he bought a 24 percent stake in Hypo Real Estate (HRE) in late July. HRE is set to become the first bank in modern German history to be nationalised.
After soaking up more than €100 billion euros in direct state aid and public loan guarantees, it needs another 20 billion in guarantees and a fresh capital injection of around 10 billion euros to stay afloat, the newspaper said on Thursday.
The German government has proposed new laws that pave the way for HRE to be nationalised by seizing shares if necessary - a taboo in Germany as it revives memories of Nazi and communist expropriations of businesses in last century.
German authorities and Flowers had not agreed on a price for his holding and tension appeared to be growing between the two sides.
Flowers wrote to German officials to express his "disappointment" and criticise the lack of any new scheduled meetings, in a letter of which the newspaper obtained a copy.
Justice Minister Brigitte Zypries said meanwhile in an interview with the business daily Börsen-Zeitung that the alternative to a nationalisation of HRE was bankruptcy.
"Each day that delays a state takeover costs taxpayers money. A lot of money," Zypries said.
The bank is a pivotal part of Germany's economy. In addition to its real-estate activities, HRE plays a key role in the issuance of Pfandbriefe, bonds in which small investors, savings banks and insurance companies have placed large sums.
Authorities fear a chain-reaction on financial markets in Germany and further afield if the bank is allowed to go under.