Greek efforts are continuing for a second day to form an urgent national unity government – aimed at keeping Greece in the euro zone and renegotiating its bailout agreement, Agence France Presse reported.
The New Democracy conservative party, which won the most seats in Sunday's general election, said it had reached a "preliminary deal" with the Socialist Pasok party.
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But Pasok, which won more than 12 percent of votes, called for the inclusion of the the left-wing, anti-austerity Syriza party, which came a close second place in the election.
Syriza has already said it would not join a government led by New Democracy.
Talks in Greece come as world leaders meeting at a Group of 20 summit in Mexico urged Europe to take "all necessary measures" to overcome the eurozone debt crisis, the BBC reported.
Jose Manuel Barroso, the President of the European Commission, said Europe's challenges were also "global."
Speaking at the G20, the German chancellor, Angela Merkel, warned that the Greek election should not call into question its commitment to a 240-billion euro bailout deal ($300 billion US), AFP reported.
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The so-called troika of the European Central Bank, the International Monetary Fund and the European Commission must be satisfied in order for Greece to receive the next installment of its bailout.
No single party won a clear majority in the Greek vote, the country's second in six weeks.