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 governing right-of-centre Democratic Alliance has won snap parliamentary elections - the third in as many years - again falling short of a majority. Its leader Luís Montenegro promised supporters to "stimulate investment" and to "guarantee prosperity and social justice".

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.