Former Greek prime minister Alexis Tsipras brushed off election polls on Friday suggesting his leftist Syriza party might lose to its conservative rival in Greece's election, saying he had a large group of supporters not reflected by pollsters.

He was speaking on the last day of formal campaigning for Sunday's general election with polls showing a cliffhanger vote expected, and some pointing to a win by the conservative New Democracy party.

Neither party, however, is expected to get the proportion of the vote needed - about 38 percent - to gain a majority in the 300-seat parliament, meaning a coalition is a near-certainty.