BRF said in a statement that the ministry initiated inspections at multiple plants without specifying how many, adding it had instructed its staff to cooperate.

The ministry of agriculture investigation follows the release earlier this month of a report by federal police claiming BRF allegedly adulterated documents to dodge food safety and quality checks.

At least six plants received inspections on Thursday, a person familiar with the matter told Reuters, speaking on condition of anonymity.

A ministry official, who also asked not to be identified, said it had opened an investigation into companies cited in a March 2018 federal police operation, codenamed "Trapaça," or "Trickery."

Trapaça investigators alleged that BRF and laboratory Mérieux NutriSciences Brasil colluded to bypass sanitary controls.

The agriculture ministry's press office had no immediate comment. Mérieux denied the fraud and corruption allegations.

Federal police also alleged that BRF tried to limit the spread of news that China had found traces of highly toxic dioxin in chicken imports from Brazil in 2015, acting to prevent a thorough government investigation.

The police accused BRF of using the forbidden antibiotic nitrofurazone and misreporting the levels of other antibiotics in its industrial processes.

BRF has said it is cooperating with the police investigation and suspended all employees named in the police report.

Authorities found evidence that BRF ordered the slaughter in 2016 of about 26,000 birds infected with Salmonella Typhimurium, a pathogen harmful to humans, and faked information provided to authorities to hide that decision.

The police said chicken from this batch was sold in at least 10 Brazilian states and exported to Europe.

The food sector probe started in March 2017 with an operation codenamed "Weak Flesh" and was expanded in March 2018 with Trapaça. The scandals disrupted production and caused the temporary closure of export markets to Brazilian meatpackers.

Police said they had still not found "undisputable" evidence yet of wrongdoing by government officials. But the agriculture ministry said 22 civil servants were implicated in the first part of the probe and 19 of them have been suspended from office pending the end of administrative proceedings.

Last week, the police indicted 43 people in connection with the criminal investigation, including a former chief executive and chairman of BRF.

Prosecutors must now decide whether to charge the people, ask for additional evidence or dismiss the police report.

Reporting by Ana Mano Editing by Dan Flynn, Susan Thomas and Diane Craft