Brazil's President Luiz Inácio Lula da Silva has won a fourth term in office in a dramatic comeback over his right-wing challenger Flávio Bolsonaro.

Left-wing leader Lula took 51.79% of votes, becoming the first president since Brazil's return to civilian rule in 1985 to be elected after losing the first round of voting.

Lula told jubilant crowds his victory was a "loss for negativity, lies", adding "long live democracy".

Flávio Bolsonaro, the son of convicted former president Jair Bolsonaro, has so far refused to recognise the result and called for it to be annulled. World leaders have congratulated Lula on his re-election.

Bolsonaro's rejection comes as no surprise to observers. His father did the same.

But a challenge appears unlikely to succeed.

Firstly, it seems to centre on the unprecedented decision by the Supreme Court Justice Cristiano Zanin to extend voting nationwide by two hours.…