Tens of thousands of Peruvians have marched against presidential candidate Keiko Fujimori, the daughter of former leader Alberto Fujimori, forcing her to suspend campaign events in advance of Sunday's elections.

Protesters fear that if she were to win the election, people who collaborated with her father will come back to power.

Alberto is serving a 25-year sentence for corruption and crimes against humanity committed during his 1990-2000 government.

At least 30,000 took part in Tuesday's march in Lima - a sign of the stiff opposition to Fujimori that could make her vulnerable to defeat in a runoff.

Fujimori is expected to win the biggest share of votes on April 10, but not the simple majority needed to win outright.

Many demonstrators derided Fujimori's recent promise never to repeat her father's "self-coup" on April 5, 1992, when he ordered the military to shutter Congress and intervened in the courts.

Fujimori had previously defended the move as needed to enact economic reforms.

"I don't believe her at all," said Rodolfo Lazo, a 19-year-old university student who had painted "I'm young but I'm not stupid" on his T-shirt.

The protesters in Lima also criticised the country's electoral board for clearing Fujimori of allegations that she broke a law against vote-buying while disqualifying two leading rivals.

"National Jury of Elections, National Shame!" one sign read.