'Polling problems' denied outright victory: Brazil's Bolsonaro

Brazil's far-right presidential candidate Jair Bolsonaro said "polling problems" during Sunday's election cheated him of outright victory.

Bolsonaro fell short of the threshold required -- 50 per cent plus one vote -- to avoid an October 28 run-off against his nearest rival, leftwing candidate Fernando Haddad.

An official tally showed Bolsonaro won 46 per cent against Haddad's 29 per cent.

"I am certain that if this hadn't happened, we would have known the name of the president of the Republic tonight," Bolsonaro said in a live Facebook video feed.

The 63-year-old former paratrooper and the longterm congressman had boasted as he voted Sunday that a run-off would not be necessary.

Although he easily won the first round, surveys suggest the outcome of the second round is uncertain, with Haddad expected to come up almost neck-and-neck with Bolsonaro as he picks up support from other beaten candidates.