Faustino Mumbika, national secretary of the opposition National Union for the Total Independence of Angola (UNITA) party, said "It doesn't exist" in response to accusations by President Joao Lourenco of party leader Adalberto Costa Junior having a financial relationship with the former president's family.
Lourenco was handpicked by dos Santos but then turned on his former patron. He is seeking a second term in the August 24 vote, which observers predict will be the tightest since Angola emerged from a lengthy civil war two decades ago.
Despite tensions, Lourenco told thousands of supporters on Thursday that all must peacefully accept the results of the election, whichever party wins.
"The current system has credible mechanisms to ensure respect for the law before, during and after elections are held," he said at a rally in the MPLA stronghold of N'dalatando, 215 kilometers east of the capital Luanda.
On Wednesday, Lourenco told a rally for his People's Movement for the Liberation of Angola (MPLA) party that UNITA was hypocritical for accusing his government of failing to tackle graft.
"They say they want to fight corruption, but they are eating from the plate of the corrupt who fled the country," Lourenco charged, alluding to some of dos Santos' children who live abroad while facing corruption and money-laundering charges at home.
Costa Junior, he added, was "allied with the corrupt".
Mumbika of UNITA dismissed the accusations as "a political game."
On coming to power in 2017, Lourenco launched an anti-corruption drive targeting dos Santos and his family -- a campaign that critics say has failed to live up to its promise.