A former German finance minister,
Peer Steinbrueck, broke with the official government line Monday and called for Greek debt to be restructured with lenders accepting losses, dpa reported.
The German government has opposed any restructuring, believing it would undermine confidence in the euro as a hard currency.
At a panel discussion at the university in Aachen, Steinbrueck, a Social Democrat, said Greece would not be able to break free of debt any other way.
He said options included both a "soft" restructuring where repayment dates were postponed or interest rates were cut and a markdown where creditors sacrificed part of the principal.
If Athens and its creditors did not negotiate this, the debt crisis would be "a horror without end," he forecast. Bailout after bailout would be needed, he said. He added that creditors should be forced to take on some risk.
"We need the creditors to participate for the sake of disciplining investors," said Steinbrueck, who was German finance minister until 2009.