U.S. President Barack Obama has spoken to German Chancellor Angela Merkel amid a worsening financial crisis in Europe as Greece heads towards a default on $2 billion of IMF loan obligations.Obama called Merkel on Sunday to discuss the developments in Greece after Greece's bailout program was not extended."The two leaders agreed that it was critically important to make every effort to return to a path that will allow Greece to resume reforms and growth within the Eurozone," a White House statement read.Obama has reportedly noted that his economic team would be carefully monitoring the situation and the leaders agreed to remain in close touch. The U.S. leader also offered his condolences over the deaths of German citizens in Friday's terror attack in Tunisia.The Eurogroup has rejected the Greek government's request to extend its bailout program for a month beyond its expiry date of June 30, to hold a July 5 referendum on bailout proposals.Greeks will vote on July 5 in a referendum on whether to accept bailout terms proposed by the Eurogroup and its other European creditors.Athens is also expected to default on its $2 billion in obligations to the IMF on Tuesday.The European Central Bank said in a statement Sunday that it would maintain the emergency loans currently available to the Greek financial system, but would offer no further aid.The ECB also said that it would maintain emergency loans at the limit agreed to on June 24 of 89 billion euros ($99.4 billion).According to the Bank of Greece, Greek banks are losing about $500 million every day as panicked savers seek access to their funds before the possible imposition of capital controls.Media have reported long lines of customers outside banks around the country as panic spreads.