A version of an artificial intelligence (AI) tool that the company said was too powerful to release to the public has just been released to the public.

Claude Fable 5 is a version of Anthropic's Claude Mythos, an AI program that raised serious concerns among technology, finance, and government leaders when it was released privately in April for preview and testing.

Some worry the tool is so powerful it could pose financial security risks, though others have questioned how much of the hype is marketing spin.

Anthropic said on Tuesday that Fable will be released with safeguards and user limitations in place, though it said, "releasing a model this capable comes with risks".

"Fable's capabilities exceed those of any model we've ever made generally available", it added.

When Mythos was first released to a small group of organisations for a preview, Anthropic said it was doing so because the tool was so intelligent that it could be dangerous due to its ability to exploit or hack computer systems.

Canadian Finance Minister François-Philippe Champagne told the BBC in April that the attention on Mythos was warranted, in part, because "it's the unknown, unknown".

Meanwhile, despite Anthropic's ongoing lawsuit against the US Department of Defence over its refusal to allow government use of its AI tools, US government agencies have been testing Mythos as well.

Anthropic is expected to become a public company soon, as its private valuation has neared $1tn (£747bn). Consistently demonstrating stronger, broader AI capabilities underscores its value to investors.

The company also said on Tuesday that the roughly 150 groups that had been given access to preview Mythos will now have access to Claude Mythos 5, which does not have limitations on cybersecurity or biology, depending on an organisation's specific uses.

To date, groups and companies using Mythos have reported to Anthropic more than 10,000 critical security flaws in their systems.

Anthropic said the updated access was limited to a "small group of cyberdefenders and infrastructure providers" but is expected to expand soon.

"We intend to expand access to Mythos 5 through a broader trusted access program", the company said.

Both Fable and Mythos, which are essentially the same model but with different safeguards and levels of access in place, can work "unattended" on human commands that the tools are given for longer periods of time "than any previous Claude models." Anthropic added.

Anthropic co-founder Jack Clark told BBC Newsnight last week that the capabilities of AI tools were expanding so rapidly that the company thought there should be a way for the public to slow the technology's advancement.

"You want the option to be able to take your foot off the gas and put your foot on the brake", Clark said. "Right now, it's like the AI industry has a gas pedal, but it doesn't have a brake pedal."