Auditors hired by Facebook to inspect the servers and systems of Cambridge Analytica have called off a search of the data firm's office at the request of UK officials.

Cambridge Analytica had agreed to a digital forensic audit in an attempt to show that it deleted certain Facebook (FB) data it held on some American users, Facebook said Monday.

Facebook asked the company to agree to an audit after The New York Times and The Observer reported that Cambridge Analytica may not have deleted certain data it had acquired about millions of Facebook users when Facebook asked it to do so in 2015.

"If this data still exists, it would be a grave violation of Facebook's policies and an unacceptable violation of trust and the commitments these groups made," Facebook said in a blog post on Monday.

Facebook had hired Stoz Friedberg, a digital forensic firm, to conduct the audit. Stoz Friedberg auditors visited Cambridge Analytica's office in London on Monday but were asked to stand down by the UK's main data protection agency, a Facebook spokesman told CNN.

The UK Information Commissioner's Office has announced it is seeking a warrant to conduct its own on-site investigation.

Although Stoz Friedberg has abandoned their search at the UK agency's request, Facebook will continue its own independent investigation, the spokesman added.

The social media giant said it also asked data scientists Aleksandr Kogan and Christopher Wylie to agree to an audit. It said that Kogan had agreed verbally, but that Wylie had yet to agree.

Kogan's company provided data on millions of Americans to Cambridge Analytica beginning in 2014. The data was gathered through a personality test Facebook application built by Kogan. When Facebook users took the test they gave Kogan access to their data, including demographic information about them like their names, locations, ages and genders, as well as their page "likes," and some of their Facebook friends' data.

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Wylie is a data scientist who previously worked for Cambridge Analytica and who provided material about the company to The Times and The Observer.

Wylie told CNN on Monday that he would be "willing to have a chat" with Facebook, though he added that it's unclear what the audit would entail.

"What is it that [they] want to audit, my phone?" He asked, adding: "I'm not a company, I don't have servers."

Facebook has said that Kogan told the company he was gathering the data for academic purposes and that by providing the data to Cambridge Analytica he breached Facebook policy. On Friday, Facebook suspended both Kogan and Cambridge Analytica from its platform. The suspension came ahead of the publication of the reporting by The Times and The Observer.

Cambridge Analytica said in a statement on Saturday that it deleted the data when Facebook asked it to do so. A spokesperson for the company did not immediately respond to a request for comment about the audit.