Apple CEO Tim Cook has taken the unusual step of going on the record to deny a news story, and is further asking the news agency that published it for a retraction.

Bloomberg News reported earlier this month that servers from San Jose-based Supermicro — which were used by many big tech companies including Apple and Amazon — were implanted with Chinese surveillance chips, and that there is an ongoing FBI investigation into the matter. Apple, Amazon and Supermicro have all denied the report, and any knowledge of a government investigation.

Thursday night, Cook told BuzzFeed News: “There is no truth in their story about Apple. They need to do that right thing and retract it.”

Bloomberg News has not returned a request for comment Friday, and neither has Supermicro.

An Apple spokesman said Friday that the company would have no additional comment. It is the first time the company has publicly called for a news story to be retracted.

Cook was adamant and detailed in his denials to BuzzFeed: “We turned the company upside down. Email searches, data center records, financial records, shipment records. We really forensically whipped through the company to dig very deep and each time we came back to the same conclusion: This did not happen.”

Lawmakers are of course asking questions about the matter — which would be a grave national security concern if true — and Apple’s chief of information security recently answered them.

“If any of the reported details cited above were true, we would have every interest— economic, regulatory, and ethical —to be forthcoming about it,” wrote George Stathakopoulos in an Oct. 8 letter to Sens. John Thune, R-South Dakota, and Ben Nelson, D-Nebraska, on the Senate Committee on Commerce, Science and Transportation, and Reps. Greg Walden, R-Oregon, and Frank Pallone, D-New Jersey, on the House Committee on Energy and Commerce.

Thursday, Director of National Intelligence Dan Coats told news site CyberScoop that he has seen no evidence of the Chinese tampering with motherboards made by Supermicro.

“We’ve seen no evidence of that, but we’re not taking anything for granted,” he told the publication.

After Bloomberg’s initial story, it reported a few days later that a U.S. telecom company had found evidence of hacked Supermicro hardware. Supermicro denied that, too.