SAO PAULO/BRASILIA (Reuters) - Antonio Galvan, head of soybean grower lobby Aprosoja, is part of a group of 10 people under investigation for their alleged role in a conspiracy against Brazilian institutions including the Supreme Court, according to court records seen by Reuters.

       According to authorities, the people under investigation have "incited the population through social networks to practice criminal and violent acts" on the eve of the Sept. 7 national holiday, when Brazilians observe Independence day.

       Supporters of President Jair Bolsonaro have called for protests at the Supreme Court that day, and officials fear they might try to force their way in to occupy the building.

       Brazil's powerful farm lobby helped elect Bolsonaro in 2018, supporting his law-and-order stance, his opposition to environmental protections and indigenous land claims. Galvan is head of an organization representing some 240,000 farmers.

       The federal police carried out 29 search and seizure warrants on Friday, according to authorities. The investigation also targeted former federal deputy and country music singer Sergio Reis, and federal deputy Otoni de Paula, among others.

       Reis could not be reached for comment. Otoni said on social media he "would not backtrack by a millimeter."

       "Aprosoja neither finances nor encourages the invasion of the Supreme Court or any acts of violence against authorities, people, public or private agencies in any city in the country," the entity said in a statement.

       A press representative for Aprosoja confirmed the raid on Galvan's home in the town of Sinop, in the farm state of Mato Grosso, saying he was not there at the time of the operation.

       A group known as "Movimento Brasil Verde Amarelo" had asked Aprosoja to support pro-government acts in May and again last week, but Aprosoja refused and that stance has not changed, the press representative said.

       Galvan did not reply to a separate request for comment.

       Supreme Court Justice Alexandre de Moraes has enforced a ban on those involved in the ongoing probe, ruling they cannot come within a 1-kilometer radius of the court building.

       The individuals under investigation are also banned from participating in any public acts and demonstrations.

       (Reporting by Ana Mano in S？o Paulo and Lisandra Paraguassu in Brasilia; Editing by Matthew Lewis)