Around 300 Brazilian police descended on the indigenous Serrinha reservation on Thursday and arrested nine suspects in a double murder inquiry linked to a dispute over renting tribal land to soybean farmers, federal officials said. The case underscores pressure to expand grain areas in Brazil, where far-right President Jair Bolsonaro has encouraged commercial farming and mining on indigenous lands, amid a tightening of global grain supplies. The Serrinha deaths occurred in mid-October among a group of around 20 ostracized members of the Kaingang tribe, which lives on the reservation, police said. They had gathered to protest against the community"s leadership, which had struck a deal allowing farmers to grow soybeans and other cash crops on the reservation. They were surrounded and surprised by an armed group of dozens of supporters linked to the leadership," the police said. The suspects shot at and killed two of the demonstrators before fleeing, police said. Investigating authorities and members of the tribe said the deal to grow cash crops on the Serrinha reservation, a 12,000-hectare (30,000-acre) area in Brazil"s southernmost state of Rio Grande do Sul, led to dissent there and in surrounding communities over how the income from it is being distributed. "The (lease) money is the cause of all disputes in the region," said Police Chief Sandro Bernardi, adding that some 4,000 hectares on Serrinha are planted with soybeans. Thursday"s arrests took place after the Justice Ministry dispatched the national security force to the reservation. read more Although challenged as unconstitutional, a 2019 settlement between indigenous affairs agency Funai, prosecutors and the Cotriserra farm cooperative has allowed leasing of reservation land for farming in Serrinha. An estimated 3 million hectares (7.4 million acres) on Brazil"s Indigenous lands are leased to plant grains, sugarcane or raise cattle, according to Funai data cited by Globo TV last Sunday. Funai, which publicly supports agriculture on tribal land, did not comment on the arrests. Reporting by Ana Mano; editing by John Stonestreet and Marguerita Choy Our Standards: The Thomson Reuters Trust Principles.