Greek Radical Left SYRIZA leader Alexis Tsipras said on Wednesday that he has failed to forge a coalition government, the second bid since the debt-laden country's fragmented election.

"We cannot form a government of the Left. We will hand back the mandate to President Karolos Papoulias Thursday," Tsipras said, passing the task to the third-placed PASOK party, led by Evangelos Venizelos.

The statement came following separate deliberations earlier in the day with Venizelos and conservative New Democracy party head Antonis Samaras.

In their statements to media, the two other leaders stressed that differences over the course the country should take regarding bailout agreements with international lenders and its economic future, had not been bridged.

Tsipras' call for annulment of terms of the deals signed with EU counterparts and International Monetary Fund since May 2010 was rejected by the leaders of the two pro-reform parties that promote "a solution that will keep Greece within the euro zone."

Venizelos, who is expected to launch a third and final round of similar talks Thursday or Friday, has proposed a national unity government of PASOK, SYRIZA, New Democracy and the Democratic Left that will guarantee the country's eurozone membership.

If Venizelos also fails, following the suit of Samaras and Tsipras, during the weekend Papoulias is expected to summon all party leaders in a final attempt to reach consensus and form a coalition.

Otherwise, Greece would head to a second round of national elections in June, a prospect that has already fuelled fears over instability and financial turmoil that could lead to a chaotic bankruptcy and exit from the European common currency zone, with a major impact on other economies.