German Chancellor Angela Merkel said Monday she was open to further negotiations with Greece, as Europe's most powerful politician sought to prevent the country's deepening debt crisis from leading to an unprecedented exit from the European common currency, according to dpa. "If the ability to find compromises gets lost, then Europe is lost," she told a conference of her Christian Democratic Union (CDU) party in Berlin. "If the euro fails, Europe fails," she said - a line she has used since the outset of the continent's debt crisis five years ago. Should leaders in Athens ask for talks after a Greek referendum planned for Sunday on the terms of its international bailout, "we will of course not rule out or ignore such negotiations," Merkel later said. International powers added to the pressure on Monday, with US President Barack Obama telling France's Francois Hollande that Greece should remain in the eurozone. During a visit to Brussels, Chinese Prime Minister Li Keqiang called for a quick breakthrough in the Greek crisis, warning that it has bearing on EU-China ties. Those comments came amid a chorus of European leaders telling the Greek public how to vote in the referendum. The July 5 vote is widely seen as choosing whether the near-bankrupt country stays in the euro. No country has left the bloc since its founding in 1999. If Greeks "vote yes, the message received in the other eurozone members, in the EU, in global society would be that Greece wants to stay together with the other eurozone and EU member states," said European Commission President Jean-Claude Juncker in Brussels. Juncker said he felt "betrayed" by Greece breaking off negotiations with its international creditors at the weekend, saying: "Selfishness and sometimes tactical, even populist, games have gotten the upper hand." In a tweet, Italian Prime Minister Matteo Renzi said the referendum should be view a "euro vs drachma" contest, rather than one pitting the commission against Greek Prime Minister Alexis Tsipras. European Parliament President Martin Schulz joined Juncker's call for the Greek population to vote "yes," arguing that the question at the heart of the vote would be "euro or no euro." Months of talks with Greece's creditors - the commission, the European Central Bank (ECB) and the International Monetary Fund (IMF) - to unlock the 7.2 billion euros (8.1 billion dollars) in aid remaining in the country's bailout were abruptly cut off late Friday. Hours later Tsipras said the government would call a referendum on the terms of a bailout deal, stunning Athens' negotiating partners and prompting the ECB to say it wouldn't increase its amount of emergency funding to the country's banks. With the ECB lifeline weakened and increasingly anxious depositors pulling money from their accounts, the government announced late Sunday that capital controls were being imposed and all banks would be closed for six days from Monday through July 7. Withdrawals from cash machines are now limited to 60 euros per day, per account. The weekend's dramatic developments could yet be eclipsed by events on Tuesday, when the European portion of Greece's bailout expires and Athens owes 1.6 billion euros to the IMF, as well as Sunday's referendum. German Finance Minister Wolfgang Schaeuble told German television ARD late Monday that he did not expected Greece to make the debt repayment. A new request by Tsipras to help extend the country's bailout programme for a few days, in order to restore the liquidity of the country's banking system, was also rejected by EU President Donald Tusk. Eurozone finance ministers had already rejected the extension request on Saturday. After an emergency cabinet on the crisis, Hollande said his country was "ready to act" to keep Greece in the 19-member currency bloc. "France is in favour of Greece staying in the eurozone, and France is ready to act," as long as there is the will on the part of Greeks to stay, he said. In a letter to German lawmakers, Schaeuble emphasized that Greece remained "an important part" of the European family and said it was up to the Greek government "to quickly find a way for an orderly and secure future." While Merkel stressed the need for Europe to find compromise amid the Greece crisis, she said fundamental eurozone principles must be adhered to. "There is again and again the question whether, for once, principles can be put aside," she said in her speech to party members. "But we have to say we can't do this ... because we want Europe to emerge stronger from this crisis than when it entered the crisis." Merkel, who has capitalized at home on her image as a steady hand in the Greek crisis, rejected holding a special summit of European leaders before Sunday's referendum in Greece. "For me, at the moment, there is no compelling reason for a special summit to be held," she said. The German Parliament is to hold a special debate on the Greek crisis on Wednesday.