German Chancellor Olaf Scholz may turn down his invitation to a major UK summit on artificial intelligence, the BBC understands.
The government is hosting an event aimed at tech leaders, academics and political leaders to discuss AI safety on 1 November.
The agenda will focus on specific future threats posed by the rapidly evolving tech, such as cyber security.
Britain has mooted setting up a global AI watchdog to monitor developments.
While no guest list has been published of an expected 100 participants, some within the sector say it's unclear if the event will attract top leaders.
A government source insisted the summit is garnering "a lot of attention" at home and overseas.
The two-day meeting is due to bring together leading politicians as well as independent experts and senior execs from the tech giants, who are mainly US based.
The first day will bring together tech companies and academics for a discussion chaired by the Secretary of State for Science, Innovation and Technology, Michelle Donelan.
The second day is set to see a "small group" of people, including international government figures, in meetings run by PM Rishi Sunak.
It will be held in Bletchley Park, the Buckinghamshire country house which was once the top-secret headquarters of World War Two codebreakers.
Though no final decision has been made, it is now seen as unlikely that the German Chancellor will attend.
That could spark concerns of a "domino effect" with other world leaders, such as the French President Emmanuel Macron, also unconfirmed.
Government sources say there are heads of state who have signalled a clear intention to turn up, and the BBC understands that high-level representatives from many US-based tech giants are going.
The foreign secretary confirmed in September that a Chinese representative has been invited, despite controversy.
Some MPs within the UK's ruling Conservative Party believe China should be cut out of the conference after a series of security rows.
It is not known whether there has been a response to the invitation.
China is home to a huge AI sector and has already created its own set of rules to govern responsible use of the tech within the country.
The US, a major player in the sector and the world's largest economy, will be represented by Vice-President Kamala Harris.
In what was seen as a political win for Downing Street, the UK-hosted AI summit was announced during an overseas trip by PM Rishi Sunak to the US in June.
Britain is hoping to position itself as a key broker as the world wrestles with the potential pitfalls and risks of AI.
However, Berlin is thought to want to avoid any messy overlap with G7 efforts, after the group of leading democratic countries agreed to create an international code of conduct.
Germany is also the biggest economy in the EU - which is itself aiming to finalise its own landmark AI Act by the end of this year.
It includes grading AI tools depending on how significant they are, so for example an email filter would be less tightly regulated than a medical diagnosis system.
The European Commission President Ursula von der Leyen is expected at next month's summit, while it is possible Berlin could send a senior government figure such as its vice chancellor, Robert Habeck.
The UK is currently planning to fold AI regulation into existing bodies: so for example, if a person feels discriminated against by an AI tool, they would contact the Equalities Commission.
But many experts in the space are calling for an international, UN-style regulator to oversee AI on a global level.
A source from the Department for Science, Innovation and Technology said: "This is the first time an international summit has focused on frontier AI risks and it is garnering a lot of attention at home and overseas.
"It is usual not to confirm senior attendance at major international events until nearer the time, for security reasons."
© OfficialAffairs
