Greece PM Papandreou faces fresh call to resign
Greece's centre-right opposition has demanded Prime Minister George Papandreou resign, throwing into disarray plans for a unity government.
Opposition leader Antonis Samaras also called for snap elections before leading his MPs in a dramatic walkout of parliament.
Mr Papandreou's government faces a crucial confidence vote on Friday.
He earlier said that opposition support could mean dropping controversial plans for a referendum on an EU bailout.
Mr Papandreou had faced a rebellion in his governing Socialist party (Pasok) over the proposed referendum, which sent markets into turmoil.
The BBC's Gavin Hewitt in Athens says Greece had seen 24 hours of political horse trading and power struggles.
Mr Papandreou's party holds a tiny majority in parliament - 152 out of 300 seats.
Last week's hard-fought EU deal to bail out debt-ridden Greece was heralded as a breakthrough.
But Mr Papandreou threw it into doubt by announcing on Monday that Greece would put the deal - which would mean crushing austerity measures - to a referendum.