U.S. Treasury Secretary Scott Bessent and Federal Reserve Chair Jerome Powell convened an urgent meeting with bank CEOs this week to warn of cyber risks posed by Anthropic's latest AI model, two sources familiar with the matter said on Thursday.

Anthropic launched the powerful Mythos model earlier this week but stopped short of a broad release, citing concerns it could expose previously unknown cybersecurity vulnerabilities.

The company has said the model is capable of identifying and exploiting weaknesses across "every major operating system and every major web browser".

Last week, Anthropic said it was in ongoing discussions with U.S. government officials about the model's "offensive and defensive cyber capabilities."

A third source close to the matter reiterated Anthropic's outreach, saying the company proactively briefed senior U.S. government officials and key industry stakeholders on Mythos's capabilities ahead of its release.

The Treasury-hosted meeting in Washington on Tuesday was aimed at ensuring banks are aware of the risks posed by Mythos and similar models and are taking steps to defend their systems, one of the sources said.

Invitations were sent while most CEOs of the largest U.S. banks were already in Washington to attend other meetings, one of the sources said.

Access to Mythos will be limited to about 40 technology companies, including Microsoft and Google, the startup has said.

Bloomberg News, which first reported the matter on Thursday, said the CEOs of Citigroup, Morgan Stanley, Bank of America, Wells Fargo and Goldman Sachs were present. JPMorgan CEO Jamie Dimon was unable to join, one of the sources told Reuters.

Goldman Sachs, Wells Fargo and the Federal Reserve declined to comment. The Treasury, lenders and Anthropic did not immediately respond to Reuters' requests for comment.