The United States on Saturday called on debt-ridden Greece to make "some tough [fiscal] decisions" leading to a quick deal with international creditors to prevent the potential breakup of the 19-nation eurozone.
U.S. Treasury Secretary Jack Lew, speaking to CNN, said Athens should act now or risk ruining the country's economy and devastating Greek society.
"I think we're at a moment now where the burden is on Greece to come back with a response that is the basis for reaching an agreement as quickly as possible," he said. The full interview is set to air Sunday on CNN's "Fareed Zakaria GPS."
The near-bankrupt Greek government needs to reach a so-called "cash-for-reforms" deal by June 30 to avoid defaulting on a $1.8 billion loan repayment to the International Monetary Fund.
Athens also owes a $7.6 billion payment to the European Central Bank in July and August, but has so far balked at austerity demands from creditors in exchange for further cash.
Negotiations remain at a standstill ahead of an emergency summit of European leaders set for Monday in Brussels.
The summit was called after multinational talks about terms of the ongoing $17.5 billion bailout ended in acrimony Thursday.
In a stopgap gesture, the European Central Bank on Friday agreed to increase emergency funding to Greek banks, after their customers withdrew more than $4 billion in the last week.
The additional $3.4 billion loan is aimed at keeping cash-starved Greek banks afloat until Monday, as world leaders await the outcome of the eurozone summit.
Washington has in recent days described "an urgent need for both Greece and its international partners to take steps towards compromise."
French President Francois Hollande said "everything" must be done to resolve the crisis based on European rules.