Brazil's federal police will formally investigate the spread of false news on social media targeting the election front-runner, far-right Jair Bolsonaro, and leftist candidate Fernando Haddad, the Public Security Ministry said Saturday.

The announcement came after the electoral court said it would look into allegations Bolsonaro had illegally sanctioned several defamatory mass messaging attacks via WhatsApp in an attempt to undermine his rival.

Bolsonaro, who is expected to win the Brazilian presidency by a landslide in the second round of voting on October 28, has denied the accusations, saying he is not responsible for what his supporters might do.

Messaging platform WhatsApp, which is owned by social media giant Facebook, has played an outsized political role in this year's presidential election.

According to a report Thursday in local newspaper Folha de Sao Paulo, several digital marketing firms have leveraged WhatsApp's encrypted services to circulate unregistered political propaganda, most of it attacking Haddad. The opposition claims the campaigns are being bankrolled by pro-Bolsonaro businessmen at the candidate's behest.

Attorney General Raquel Dodge said "the specialized and structured use of business logistics in the mass disclosure of false information" constitutes a criminal offense, adding that it could also damage the candidates' reputations and interfere with the opinions of voters.

This new format of crime and those behind it need to be investigated by a highly qualified expert body, she said.

Enough to sway voters?

It remains unclear whether the accusations have had any bearing on opinion polls. The latest survey, taken before the initial report was published, showed Bolsonaro enjoying 59 percent of the vote, compared to Haddad on 41 percent.

Since then, however, the allegations appear to have energized Haddad's campaign. His leftist Workers' Party claims it has witnesses saying Bolsonaro had asked business leaders for cash to pay for the bulk messaging. That, they allege, amounts to illegally soliciting undeclared campaign contributions.

WhatsApp is among the most preferred messaging and social media apps in Brazil, which is home to roughly 120 million users. However, it has come under increasing scrutiny in the country as the main medium for disseminating fake news. While platforms like Facebook and Twitter are easier to police, WhatsApp users exchange information directly over an encrypted network.

WhatsApp vows to fight on 'illegal' mass messages

Reacting to the report, WhatsApp announced Friday that it was taking "immediate legal action to stop companies from sending bulk messages."

The tech company said previously it had banned hundreds of thousands of accounts inside Brazil found to have engaged in spam or automated "bot" behavior ahead of the election. One of those accounts belongs to Bolsonaro's son, although the ban has since been lifted.

WhatsApp confirmed that it had blocked Flavio Bolsonaro for "spam behavior" and reasons unconnected to the Folha report.

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nm/cmk (AFP, EFE, Reuters)