Brazil's leader gains ground in tight race

Brazil's President Dilma Rousseff is gaining ground over her rival in a tight re-election race, a poll shows, although the contest remains in a technical tie.

The Datafolha polling group's latest survey has Rousseff with 52 per cent of voters' support, compared to 48 per cent for challenger, Aecio Neves.

With the margin of error at two percentage points, that keeps the pair statistically tied.

But the poll was the first to show Rousseff numerically in front of Neves - meaning she's trended upward while Neves has slipped.

The previous poll by Datafolha released late last week had the race at 51-to-49 in Neves' favour.

Monday's poll also captured a rising rejection rate for Neves: 40 per cent of those surveyed said they would never vote for Neves, compared to a rejection rate of 34 per cent earlier this month.

Rousseff's rejection rate stood at 39 per cent in the most recent poll - down from 43 per cent earlier this month.

This year's campaign is considered by many analysts to be the most surprising and closely contested since Brazil's return to democracy nearly 30 years ago.

Datafolha says it interviewed 4389 electors across Brazil on Monday.