BERLIN — The German chancellor, Angela Merkel, suggested Friday that Greece hold a referendum on remaining in the euro zone during a telephone call with the Greek president, Karolos Papoulias, a government spokesman in Athens said, but a spokesman for the chancellor denied she had made the suggestion.


The spokesman, Dimitris Tsiodras, said Ms. Merkel made the suggestion that a referendum be held in parallel with general elections scheduled for June 17 as a means to gauge the extent to which Greeks want to remain in the euro zone. The spokesman added, however, that holding such a referendum did not fall within the remit of Greece’s caretaker government.


A spokeswoman for Ms. Merkel’s office denied the chancellor had suggested a referendum. Earlier in the day, a spokesman for the chancellor, Georg Streiter, confirmed the conversation with the Greek president. According to Mr. Streiter, she had reiterated to Mr. Papoulias, that “it is the wish of Germany and all European partners that a capable government be built as quickly as possible after these elections.”


With an interim government now in place and only four weeks to go until the next round of parliamentary elections in Athens, a broad effort is under way by Germany and its European Union partners to make it clear to Greek voters exactly what is at stake when they cast their votes next month.


Germany finds itself in a delicate position, not wanting to appear to be interfering in the election — which would encourage the opposition forces that failed to form a government after the last election — while simultaneously using all possible channels to communicate to Greek voters that their country’s future in the 17-member euro zone depends on electing a government that will uphold the country’s loan agreement with the European Union, European Central Bank and the International Monetary Fund.


The fallout from the uncertainty in Greece continued to upset markets across Europe on Friday, as top E.U. officials contradicted each other on the possibility of a Greek exit from the euro and a leading ratings agency downgraded 16 Spanish lenders.


Comments by an E.U. official, who joined businesses and financial firms in signaling that contingency plans are being drafted to deal with the potential fallout of a Greek exit, indicated how real the readiness to cut Greece loose may be. “Today there are, both within the European Central Bank and the European Commission, services that are working on emergency scenarios in case Greece doesn’t make it,” the European trade commissioner, Karel De Gucht, said in an interview published Friday in the Belgian newspaper De Standaard.


Mr. De Gucht’s comments prompted a rare public rebuke from a colleague, illustrating how raw nerves have become over the uncertainty surrounding Greece, which saw its credit rating downgraded further into junk territory by Fitch Ratings late Thursday, on concern over a lack of public and political support for the country’s bailout.


“Karel De Gucht is responsible for trade. I am responsible for financial and economic affairs and relations with the E.C.B.,” the vice president of the European Commission, Olli Rehn, said during an event in London. “We are not working on the scenario of a Greek exit. We are working on the basis of a scenario of Greece staying in.”


E.U. offices in Brussels were closed Friday and a spokesman for Mr. De Gucht did not respond to messages seeking comment.


While continued support for Athens remains the official line, many influential Germans would like to see Greece driven from the euro zone — some as an example to other countries, and others because such an exit would allow the country to recover from its fiscal woes. If Syriza, the party that opposes the terms of Greece’s current bailout plan, were to come out ahead in the next election and overplayed its hand, Greece could find itself with an invitation to leave.


“There is a good argument for the view that Greece is the basket case — to be very frank and plain — get rid of them and the other countries’ politics and economics are much sounder,” said Jürgen Matthes, senior economist at the Cologne Institute for Economic Research.