Portugal’s third general election in three years has failed to deliver the result that could break the worst spell of political instability for decades in the European Union country of 10.6 million people.

Portugal's ruling centre-right Democratic Alliance was poised to win the most votes in an early parliamentary election on Sunday, but short of a full majority, exit polls showed, paving the way for more political instability in the country.

Incumbent Portuguese Prime Minister Luis Montenegro and Socialist party leader Pedro Nuno Santos cast their votes on Sunday in Portugal's general election. Voters are returning to the polls for a third general election in three years,