Brazil's far-right presidential candidate has opened up a 10-point lead over his rivals ahead of next week’s election.

Jair Bolsonaro is currently leading his opponent Fernando Haddad, a candidate from the leftist Workers Party, and would tie in a second-round runoff against him next month, an opinion poll showed on Monday.

Mr Bolsonaro, who is recovering from a near-fatal stabbing, has increased his lead ahead of the election on 7 October with 31 per cent of voter support in a first-round ballot, the survey by polling firm Ibope said.

In the likely case of no candidate receiving more than 50 per cent of the vote, there will be a second-round runoff which take place at the end of the month on 28 October.

Polls show that in the case of a runoff vote, Mr Bolsonaro and Mr Haddad are both on 42 per cent, with the remaining voters either undecided or saying they would annul their ballots.

Mr Haddad’s support initially surged after he replaced jailed former President Luiz Inacio Lula da Silva on the Workers Party ticket, who was banned last month by an electoral court from running from prison, but his support remained stagnant compared to the same Ibope poll last week.

Support for centre-left candidate Ciro Gomes remained stable at 11 per cent, while business-friendly former Sao Paulo governor Geraldo Alckmin dropped to 8 per cent, according to Ibope.

The poll, published by the Estado de S.Paulo newspaper and TV Globo, surveyed 3,010 voters across Brazil on 29 and 30 September. It has a margin of error of two percentage points.

Agencies contributed to this report