Brazilian prosecutors have moved to ban President Jair Bolsanaro’s son from becoming ambassador to the US.
The public prosecutor’s office filed an injunction on Monday asking a federal court to rule on the experience needed for anyone to serve as a diplomat.
Opposition lawmakers have also asked the Supreme Court to block the appointment, calling it nepotism.
It comes days after Mr Bolsonaro said US President Donald trump had approved the appointment of his son, Eduardo.
However, the nomination still requires approval from Brazil’s Senate.
According to Brazilian magazine Epoca, prosecutors asked a court in Brasilia to rule on the “merits and services” required for any non-diplomats serving as ambassadors.
The prosecutors added that there would be “danger of harm if a person is nominated without adequate preparation”.
Eduardo Bolsonaro, 35, is a congressman who heads the foreign affairs committee in the lower house.
He has no previous diplomatic experience, but has been dubbed Brazil’s “shadow foreign minister” because of the strong influence he has on his father’s foreign policy, BBC Americas editor Candace Piette reports.
Earlier this year, he joined his father in a private meeting with US President Trump during a diplomatic trip to Washington.
Both the president and his son have a pro-US stance, breaking with Brazil’s traditionally more cautious position. Eduardo is openly pro-Israeli, whereas in the past Brazil has been careful not to offend Arab nations.
President Bolsonaro has defended Eduardo’s nomination as ambassador, saying his son is a friend of the Trump family, which would help strengthen ties between the two countries.
Last week, the Brazilian president said he had received a handwritten letter from President Trump approving the nomination, describing it as “a great appointment”.
Mr Bolsonaro uses several of his relatives as advisers. His eldest son, Flavio, is a senator, while Carlos Bolsonaro is a Rio de Janeiro city council member.
Mr Trump is also known for appointing family members to political positions. On the White House website, his daughter Ivanka Trump is listed as an adviser to the president, focusing on “the education and economic empowerment of women and their families as well as job creation and economic growth”.