Greece's Prime Minister George Papandreou arrives at a news conference at the end of a euro zone summit in Brussels in this October 23, 2011 file photo. [Photo/Agencies]

Greek Prime Minister George Papandreou is under pressure to stand down on Thursday amid a growing "rebellion" by ministers and ruling party deputies who joined the opposition calling for a national unity government and snap general elections.

As Papandreou chaired an extraordinary cabinet meeting, local media reported, citing party sources, that he might visit Greek President Karolos Papoulias later on Thursday in a sign that he will submit his resignation or ask for a unity government,

However, his close aid Regina Vartzeli told reporters that he does not plan to resign.

But the climate is tense in Athens since early Thursday, when Deputy Prime Minister and Finance Minister Evangelos Venizelos opened a wave of unprecedented criticism against the prime minister over his surprise call on Monday for a referendum on the EU aid package.

Ahead of a confidence vote planned for Friday night, a dozen of leading cabinet ministers publicly broke ranks with Papandreou, rejecting the referendum idea and accusing him of mishandling the crisis.

Education Minister Anna Diamantopoulou said the prime minister has dragged himself and the country to "a public insult" made by German Chancellor Angela Merkel and French President Nicolas Sarkozy during a meeting in Cannes on Wednesday night.

According to parliamentary sources, a group of ruling PASOK party deputies in collaboration with main opposition conservative New Democracy (ND) party legislators promoted a joint appeal for the imminent creation of a national salvation government.

In a statement Thursday noon, ND leader Antonis Samaras called for a transitional administration to take office until the parliament ratifies the latest EU deal on further vital financial support for Greece and the holding of early elections in coming weeks instead of a referendum.

Right-wing Popular Orthodox Rally (LAOS) party leader Yorgos Karatzaferis supported calls for the formation of a national unity, while the two Left parties represented in the parliament turned down the idea, insisting on snap elections immediately.

Local analysts noted that even if Papandreou survives the revolt within the cabinet on Thursday, he risks losing the confidence vote on Friday, since from early Thursday at least three ruling party deputies warned that they would cast negative votes.

PASOK held a slim two-seat majority in the 300-member assembly, before the outbreak of the trust crisis with Papandreou.