Voting has begun in Greece's general election, with opinion polls indicating a tight race between the left-wing incumbent Syriza party and the conservative New Democracy.

The Greek parliament has backed the country's new bailout deal after all-night talks, despite a rebellion by many MPs in the governing Syriza party.

Greece's parliament on Thursday passed legislation on a second batch of reforms needed to help unlock a huge international bailout for the country's stricken economy.