Brazil has denied visas for two US officials who sought to meet with Brazilian election authorities less than three months before a tense presidential vote, a diplomatic source told AFP news agency.

The Brazilian source, who spoke on condition of anonymity, cited a "risk of political exploitation" as being behind the decision.

It comes after Brazil's right-wing candidate Flavio Bolsonaro renewed claims this week that the country's electronic voting system is insecure.

The source said the US request was filed on July 20, with the two officials hoping to discuss issues of "freedom of expression related to the elections" with local authorities.

It "caught people's attention" that the visa request came the same day Flavio Bolsonaro held a private meeting with foreign diplomats, during which he reportedly questioned the reliability of Brazil's electronic voting system, the source added.

Flavio Bolsonaro's father, ex-president Jair Bolsonaro, was barred in 2023 by electoral authorities from running for office after he raised similar claims the year prior, while still in the presidency.

He was later convicted for plotting a coup following his 2022 election loss and is serving a 27-year sentence under house arrest.