Greek leader offered to resign amid nation-wide upheaval

Papandreou instead held talks via telephone with the head of the conservative New Democracy party, Antonis Samaras, on forming a national unity government.

Sources earlier in the day had suggested that Samaras did not oppose such a cross-party alliance but that Papandreou would have to go, a move the Athens News Agency reported the prime minister was open to.

The EU-IMF-ECB troika has for weeks now publicly pressed the government and opposition to come to a cross-party consensus on the main elements of a deal to deliver a second bail-out to the country.

However, Samaras reportedly also demanded significant changes to the agreement with international creditors.

Papandreou said that his efforts to build a coalition government was the fourth such attempt he had made, and lashed out at his opposite number, blaming him for their failure.

"Today I made new proposals to the leaders of all parties to achieve the necessary national consensus," he said, "But before the substance of the matter had been discussed, certain conditions were made public that were unacceptable."

The prime minister's announcement came as the country was bludgeoned by another general strike and attempts by the so-called indignant protesters to prevent MPs from entering parliament for the presentation of another round of austerity.

In the capital, some 15,000 police attempted to disperse thousands of demonstrators, firing tear gas to clear the square in front of parliament while small-scale skirmishes broke out on the edges of the plaza.

Demonstrators claimed that masked individuals provoking the violence, sequestered by peaceful protesters, were found to have police identification.

Water cannon and iron barricades were deployed to give deputies access to the building, with a number of politicians disguised or riding mopeds instead of driving cars in order to pass through.

Government sources claimed that "everybody got through" the Athens blockade. Nevertheless, the leader of the liberal Democratic Alliance party, Dora Bakoyanni, said that there were only 30 MPs in the chamber, including herself.

Across the country, similar protests occupied or blocked access to government buildings.

Banks, schools, transport and much of the public sector were shut down by widespread walk-outs. Flights however continued as normal.