The UK’s AI Security Institute (AISI) won’t be granted access to test new OpenAI and Anthropic models, according to reports, marking the second blow for the testing agency this month.
On 22 September, the duo launched a series of new models, with Anthropic unveiling Claude Opus 5.5 and OpenAI introducing GPT-6 Sol and GPT-6 Luna.
Backed by the UK government, the AISI is tasked with conducting research into AI model safety and works closely with industry stakeholders and researchers.
While the AISI has typically tested models before they’re released publicly, reports from suggest the White House asked both firms not to share these until they had undergone testing by US authorities.
Citing sources familiar with the matter, noted the request came from the Office of the National Cyber Director. Sources told the publication that US officials want to review both models before being shared with international partners.
A senior US official told that the justification behind the move was that “they’re American companies and this has been our policy with every new frontier model that comes out”.
approached both companies for confirmation, but did not receive a response by time of publication.
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We will update this article accordingly upon receiving comment.
Another blow for the AISI
If confirmed, the move by the duo marks the second blow for the AI testing institute in the space of a month. As reported in early September, the AISI was not granted access to Anthropic’s Mythos 5.1 model for pre-release testing.
The AI developer declined to submit the model for testing despite having granted access to similar US entities. The move marked the first time the AISI had been left out of pre-release evaluations of Anthropic models.
Claude Mythos 5.1 launched on 1 September, and as with other recent models, only approved partners were given access amidst security and safety concerns.
At the time, reports from the , citing UK government officials, suggested the move pointed toward a “wider protectionist shift” among US tech companies.
The AISI has been granted access to test recent GPT-6 range models. In a letter to Liam Byrne, chair of the House of Commons Business and Trade Committee, AISI director Henry de Zoete noted that the institute had conducted testing on OpenAI’s GPT-6 Astra model before it was released to the public.
In that letter, de Zoete noted that the AISI wasn’t the only organization denied access to testing.
“Anthropic made clear at the time of the release of Mythos 5.1 that no organisations outside of the US had access to the model,” de Zoete wrote.
“AISI is in daily conversation with industry partners, including Anthropic, and maintains long-standing arrangements to test models from major AI developers.”
A spokesperson for the AISI told : ““The UK is a world leader in AI security, and the AI Security Institute continues to work closely with the US government, international partners and leading AI companies, including OpenAI and Anthropic.
“These risks do not stop at national borders and no country can tackle them alone. We will continue to work closely with the US and other partners on the testing of advanced AI, while building our own rigorous scientific understanding of these systems and ensuring our approach is grounded in the evidence.”