Greece failed in its efforts to forge a "pro-European" Government after a watershed election in which nearly two-thirds of voters rejected the reform programme which has underwritten the country's international bailout.
The prospect of stalemate in Athens, fresh elections next month and a possible exit from the euro sent markets plunging, while Angela Merkel, the German Chancellor, warned that Greece must stick to its commitments to international lenders or face default.
Greece's two main parties were locked in talks over a Government of national unity but a collapse in their support left them with only one-third of the vote, no parliamentary majority and no obvious coalition partner.
Antonis Samaras, leader of first-placed party New Democracy, announced that he had done "everything possible" but had failed to build a coalition, handing the mandate back to the President "We directed our proposal to all the parties that could have participated but they either directly rejected their participation, or they set as a condition the participation of others who, however, did not accept."
Should the country fail to secure its next tranche of loans in June it would be forced into bankruptcy and out of the euro.