The Trump administration has lifted restrictions on artificial intelligence company Anthropic's latest Claude AI models after a temporary ban prompted by cybersecurity concerns.

Anthropic said Tuesday that its Claude Fable 5 model is once again widely available. The company is also restoring access to its most advanced model, Mythos 5, but only for a limited number of US-based organisations approved by the federal government.

The US Commerce Department had blocked foreign nationals from accessing both AI models on June 12. Anthropic said the decision forced it to suspend the products for all users just days after launching them.

In a blog post, the San Francisco-based company said the government's concerns stemmed from findings by cybersecurity researchers at Amazon, its main cloud computing partner.

According to Anthropic, the researchers discovered a way to bypass the safety protections built into Claude Fable 5, allowing the system to identify and potentially exploit software vulnerabilities.

US officials have become increasingly cautious after Anthropic warned earlier this year that its Mythos AI model was highly capable of detecting software weaknesses that could be misused by hackers to target critical computer systems.

Meanwhile, Anthropic's main competitor, OpenAI, announced on Friday that it is also limiting the release of its latest AI model at the request of the Trump administration.

OpenAI said its new model, GPT-5.6 Sol, will initially be available only to a small group of government-approved users for a temporary period.

Last month, President Donald Trump signed an executive order creating a framework for the federal government to review the national security risks of the most advanced AI systems for up to 30 days before they are released publicly.

Although participation in the review process is voluntary for AI developers, the administration has yet to fully implement the new framework.