Merkel spoke with Greek President Karolos Papoulias on Friday, after which the Greek government said she had made such a suggestion, which her office immediately denied.
But the Süddeutsche Zeitung reported on Saturday that the euro finance ministers had quietly given their Greek colleague Philippos Sachinidis the task of “creating the possibility of talking about a referendum in Athens.”
No politician has spoken openly about the idea. Merkel took the time on Friday to “inform [Papoulias] of the situation,” the paper said.
Der Spiegel magazine backed the claims, saying Merkel had suggested a referendum be held alongside general polls.
Der Spiegel however insisted the chancellor did indeed make the suggestion and added the idea had already been floated by German Finance Minister Wolfgang Schäuble during a meeting with his eurozone counterparts on Monday.
He had argued that a "yes" vote in a referendum on eurozone membership should also be an endorsement of the austerity measures decided by the previous Greek government, the news magazine reported, without naming its sources.
Merkel's purported suggestion caused a stir in Greece, where political leaders have repeatedly complained of German interference.
“The Greek people have no need for a referendum to demonstrate their choice for the euro, they have already made enough costly sacrifices to show that," said Antonis Samaras, leader of the conservative New Democracy party which won inconclusive May 6 polls.
Merkel's suggestion, "above all coming in the run-up to the election, is regrettable and unacceptable," Samaras said in a statement. "The Greek people have the right to respect from its (European) partners."
Until now, Merkel has insisted that Greece must stick to the austerity terms in the bailout deal or risk losing access to debt funding – effectively forcing it out of the eurozone.
But in recent months, calls for the focus to be rebalanced towards growth have increased, notably with Francois Hollande's election as French president.