RIO DE JANEIRO (Reuters) - Police detained an executive of BRF SA on Saturday, as the meat company and rival JBS SA took out full-page advertisements to burnish their image after raids to investigate alleged bribes paid to conceal unsanitary conditions in Brazil's meatpacking facilities.

Roney Nogueira, a government relations executive with BRF, turned himself into police for questioning at Guarulhos airport in Sao Paulo, according to a BRF spokesman. The company, along with JBS, is part of a massive meatpacking industry that in recent years made Brazil one of the world's top exporters of meat.

Police sought Nogueira, who was returning to Brazil from South Africa, because he allegedly discussed bribing health inspectors, including one who helped prevent the closure of a plant in the state of Goiás, according to court documents.

Police said Friday's raids were prompted by evidence that some meatpackers had paid inspectors and politicians to overlook the processing of rotten meat and exports with fraudulent documentation and even traces of salmonella.

Highlighting the importance to Brazil of agriculture, one of the few vibrant sectors in an economy still struggling from two years of recession, President Michel Temer is scheduled to meet with meat industry executives on Sunday, a government spokeswoman said.

On Saturday, JBS and BRF launched a public relations offensive to deflect a crisis that threatens an industry with $12 billion in annual exports.

In a statement late on Saturday, BRF said some allegations made by police were false or based on faulty understanding. "BRF never sold rotten meat," the company said, adding that mentions of spoiled or contaminated products by police were specifically tied to smaller meatpackers unrelated to the company.

JBS, the world's largest meat producer, in advertising Saturday made similar clarifications, noting that allegations of "adulterated products do not involve any JBS brands."

"Quality is the foremost priority of JBS and its brands," read one of its full-page advertisements in publications that included the major dailies of São Paulo and Rio de Janeiro.

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In an email, a JBS spokeswoman said the ads, which also include radio and television spots, would run across 27 different media outlets through Monday.

BRF, for its part, ran ads addressing "the millions of consumers whose confidence we have earned," vowing to adhere to the principles of "truth, respect, quality and transparency."

The detection of salmonella in four containers of meat shipped from a BRF plant to Italy violated no regulations in Brazil or Europe, the company said in its separate statement to the media, adding that the strain of the bacteria was considered safe by regulators.

BRF also said allegations that cardboard had been found in its sausage meat were false.

João Gomes Cravinho, the European Union's ambassador to Brazil, said Saturday the bloc had asked Brazilian officials for more information about Friday's raids and whether the problems indicated a systemic problem or isolated incidents.

"We have to protect the safety of consumers," he said.

Investors on Friday hammered shares of both companies after news of the raids. JBS plunged 11.0 percent, while BRF fell 7.0 percent at the Sao Paulo stock exchange.

(Reporting by Paulo Prada; Editing by Marguerita Choy and Tom Brown)