President of the Superior Electoral Court Rosa Weber, talks with the President of the Workers' Party Gleisi Hoffmann, during a meeting with the leadership of the Workers' Party, at the Supreme Electoral Court headquarters, in Brasilia, Brazil, Friday, Oct. 19, 2018. The Haddad campagin accused far-right adversary of illegal campaign practices for allegedly allowing friendly businessmen to secretly pay to spread slanderous messages. (AP Photo/Eraldo Peres)

The messaging service WhatsApp says it has sent "cease and desist" letters to stop companies from sending bulk messages related to Brazil's election and banned their accounts.

The actions come after a report that businessmen linked to leading far-right candidate Jair Bolsonaro allegedly bankrolled a campaign that planned to spread on WhatsApp to benefit his candidacy. His rival, Fernando Haddad, has asked Brazil's electoral court to investigate.

WhatsApp said Friday that it has banned hundreds of thousands of accounts using spam-detection technology to identify "" since the Brazilian electoral period began in August.

The company said the account of Bolsonaro's son, Flavio, was banned a few days earlier because it was spamming users. Flavio Bolsonaro said Friday that his account has now been unblocked.

  • President of the Superior Electoral Court Rosa Weber, right, listens to questioning from lawyers representing Fernando Haddad's campaign, during a meeting with the leadership of the Workers' Party, at the Supreme Electoral Court headquarters, in Brasilia, Brazil, Friday, Oct. 19, 2018. The Haddad campagin accused far-right adversary of illegal campaign practices for allegedly allowing friendly businessmen to secretly pay to spread slanderous messages. (AP Photo/Eraldo Peres)

  • President of the Superior Electoral Court Rosa Weber, listens to questioning from lawyers representing Fernando Haddad's campaign, during a meeting with the leadership of the Workers' Party, at the Supreme Electoral Court headquarters, in Brasilia, Brazil, Friday, Oct. 19, 2018. The Haddad campagin accused far-right adversary of illegal campaign practices for allegedly allowing friendly businessmen to secretly pay to spread slanderous messages. (AP Photo/Eraldo Peres)

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