German news weekly Der Spiegel reports that the country's central bank believes international creditors will have to agree a new bailout for Greece by early next year.
The move would come months after Germany's Sept. 22 general election. Chancellor Angela Merkel's conservative government has been at pains to appear firm on Greece's international bailout, which is unpopular with many Germans.
Der Spiegel reports Sunday that the Bundesbank told Germany's Finance Ministry and the International Monetary Fund that a recent 5.7 billion euros ($7.62 billion) payment to Greece was approved "due to political constraints."
The central bank reportedly also described the risks of the current rescue program for Athens as "unusually high" and the performance of the Greek government as "hardly satisfying."
A Bundesbank spokeswoman declined to comment on the report.