Greece's election favourite Alexis Tsipras, the head of the radical left Syriza party, urged voters to end the "national humiliation" by giving him a clear mandate to tear up austerity.

Addressing a crowd of supporters in Athens for his keynote speech ahead of Sunday's elections, Tsipras said that an outright victory of his party would emancipate Greece from strict, EU-imposed economic measures.

"On Monday, national humiliation will be over. We will finish with orders from abroad," Tsipras said, Reuters reported. "We are asking for a first chance for Syriza. It might be the last chance for Greece."

Syriza, a leftist coalition including Marxists, Trotskyists and Greens, is leading polls. The party is offering Greeks, who are facing wage and pension cuts as well as unemployment rates of more than 25%, a message of optimism, mixed with confrontational tones towards the EU and the IMF.

"Hope has arrived and will write history," he told an Athens rally, local newspaper Ekathimerini reported. "Nothing can stop it now."

"The time of the left has come," he added, as he was joined on stage by Spain's populist Podemos party leader Pablo Iglesias.

The anti-establishment party has campaigned heavily against austerity measures imposed by an EU-IMF plan as part of a loan package to rescue the country from the brink of bankruptcy.

Tsipras argues the loan terms are far too punishing and ought to be renegotiated and has promised to make public investments and increase government spending.

According to a poll by Metron Analysis Syriza is set to win 36% of the vote, with a 5.3 points lead over Prime Minister Antonis Samaras's centre-right New Democracy party.

Tsipras's party polled first in another three surveys conducted in recent days, with leads ranging from four to six points.

Political uncertainty related to a possible Syriza victory could result in a forced exit of Greece from the eurozone, according to some analysts.