Some eurozone governments are concerned highly indebted Greece will not be able to refinance itself and may have to restructure its debt, the Financial Times Deutschland reported on Wednesday.
The newspaper said representatives of several eurozone governments told the paper that a restructuring could no longer be ruled out.
The business daily did not name its sources or the countries involved.
"An extension and top-up of the aid package would not be politically possible. Then, consequences would have to be drawn," the paper quoted a source in the finance ministry of a large eurozone country as saying.
It also quoted an advisor to the leader of an EU state as saying: "We must have a plan B ready" for the possibility Greece requires more financial assistance.
Greek and European officials have long insisted that Greece can recover without restructuring its debt, and that even discussing a restructuring now would be counterproductive by damaging banks across Europe and causing panic in markets.
On Saturday, the International Monetary Fund denied a report in German magazine Der Spiegel that it was privately pressing Greece to restructure its debt.