British Prime Minister Rishi Sunak, U.S. Vice President Kamala Harris, EU chief Ursula von der Leyen and U.N. Secretary-General Antonio Guterres were all set to attend the two-day conference, which focuses on growing fears about the implications of so-called frontier AI.
The release of the latest models have offered a glimpse into the potential of AI, but have also prompted concerns around issues ranging from job losses to cyber attacks and the control that humans actually have over the systems.
Sunak, whose government initiated the gathering, said in a speech last week that his "ultimate goal" was "to work towards a more international approach to safety where we collaborate with partners to ensure AI systems are safe before they are released.
"We will push hard to agree the first ever international statement about the nature of these risks," he added, drawing comparisons to the approach taken to climate change.
But London has reportedly had to scale back its ambitions around ideas such as launching a new regulatory body amid a perceived lack of enthusiasm.
Italian Prime Minister Giorgia Meloni was one of the only world leaders, and the only one from the G7, attending the conference.
'Talking shop'
While the potential of AI raises many hopes, particularly for medicine, its development is seen as largely unchecked.
In his speech, Sunak stressed the need for countries to develop "a shared understanding of the risks that we face."
But lawyer and investigator Cori Crider, a campaigner for "fair" technology, warned that the summit could be "a bit of a talking shop."
"If he were serious about safety, Rishi Sunak needed to roll deep and bring all of the UK majors and regulators in tow, and he hasn't," she told a press conference in San Francisco.
"Where is the labor regulator looking at whether jobs are being made unsafe or redundant? Where's the data protection regulator?" she asked.
More than 100 signatories of an open letter published on Monday also warned that "the communities and workers most affected by AI have been marginalised by the summit," bemoaning the lack of involvement of civil society organisations.
Having faced criticism for only looking at the risks of AI, the UK on Wednesday pledged 38 million ($46 million) to fund AI projects around the world, starting in Africa.
Ahead of the meeting, the G7 powers agreed on Monday on a non-binding "code of conduct" for companies developing the most advanced AI systems.
In Rome, ministers from Italy, Germany and France called for an "innovation-friendly approach" to regulating AI in Europe, as they urged more investments to challenge the United States and China.
Vice President Harris was also on Wednesday to announce the creation of the United States AI Safety Institute (US AISI), which will "create guidelines, tools, benchmarks, and best practices" for identifying and mitigating AI risk, her office said.
China was also due to be present, but it was unclear at what level.
News website Politico reported London invited President Xi Jinping to signify its eagerness for a senior representative.
The invitation has raised eyebrows amid heightened tensions between China and Western nations and accusations of technological espionage.
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