A hacker on Tuesday published a trove of Hillary Clinton-related documents claimed to be stolen in the Democratic National Committee (DNC) breach.

Guccifer 2.0 — who claims to be the hacker behind the breach — posted a file purporting to be a database of Clinton Foundation donors who had made large contributions and a dossier of ways to defend her against political attacks.

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The Hill could not immediately verify the authenticity of the documents.

The self-proclaimed hacker appeared online the day after the breach was first exposed publicly, claiming that he had stolen thousands of documents from the DNC.

But according to CrowdStrike, the security firm investigating the breach for the committee, two separate Russian government hacking groups that did not appear to be working together infiltrated the DNC’s systems.

“These claims do nothing to lessen our findings relating to the Russian government’s involvement,” the firm said last week.

One group, which the firm has nicknamed “Fancy Bear,” is responsible for the theft of opposition research on presumptive Republican presidential nominee Donald Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE and is believed to work for Russia’s military intelligence service.

A separate group, nicknamed “Cozy Bear,” reportedly accessed the committee’s internal emails and chats.

Both groups were highly sophisticated and able to avoid normal security protections, CrowdStrike said.

The DNC has painted Guccifer 2.0’s claims as a Russian disinformation campaign.

In an interview with Motherboard, Guccifer 2.0 claimed to be from Romania.

Asked if he worked with the Russian government, he replied: "No because I don't like Russians and their foreign policy. I hate being attributed to Russia."