(Adds JBS confirmation it will appeal, recasts lead paragraph)
BRASILIA, July 3 (Reuters) - A Brazilian Supreme Court justice rejected an appeal from the world's largest meatpacker, JBS SA, to overrule a lower-court ruling that halted the sale of $300 million worth of South American assets to Minerva SA, according to a court document.
Justice Edson Fachin's decision upholds a lower court's ruling that JBS' deal to sell plants in Argentina, Paraguay and Uruguay could harm the investigation of a massive corruption scandal involving JBS.
Fachin's final decision was made on Friday, although the full ruling has yet to be released. JBS said in an emailed statement it would appeal the matter to the full Supreme Court.
Prosecutor-General Rodrigo Janot reached a plea agreement in May with the billionaire brothers who control JBS, Wesley and Joesley Batista, to avoid prosecution if they turned in 1,893 politicians allegedly involved in a bribery scheme.
Their testimony led to last week's corruption charge against President Michel Temer. The charge against Temer, who has repeatedly denied any wrongdoing, added to the political turmoil in Latin America's biggest economy and threatens to halt the president's economic reform agenda in Congress.
JBS lawyers had argued before Fachin that blocking the sale of assets to Minerva broke the terms of the plea-bargains the Batista signed, which gave them immunity against prosecution.
A separate leniency deal between the Batistas and federal prosecutors was signed in late May, requiring the family to pay a 10.3 billion reais ($3.11 billion) fine over 25 years.
($1 = 3.3124 reais) (Reporting by Ricardo Brito; Editing by Frances Kerry and Bill Trott)