EVIAN : G7 leaders on Wednesday hailed the US-Iran deal to end the Middle East war as a "historic opportunity" and agreed to increase pressure on Russia over its invasion of Ukraine, ahead of an unusual summit session with AI bosses to discuss online security.

The three-day meeting of the leaders of Britain, Canada, France, Germany, Italy, Japan and the United States has focused intensely on US President Donald Trump's deal to end the war with Iran and efforts to pressure Russia into brokering peace with Ukraine.

France, whose President Emmanuel Macron is chairing the G7, published a communique overnight that said all the leaders had agreed on key geopolitical issues.

Trump's memorandum of understanding with Iran, to be signed in Switzerland on Friday, "provides an historic opportunity to prevent Iran from acquiring any nuclear weapon and tackling the threats related to its regional and ballistic activities", it said.

A multinational force led by France and Britain "can play an important role to facilitate the resumption of maritime traffic" in the Strait of Hormuz, where shipping has been severely restricted in the conflict, it added.

Canadian Prime Minister Mark Carney, speaking before the third day got underway, said there was "a likelihood that this memorandum of understanding agreement could be a game-changer".

As well as increasing the supply of air defence equipment to Ukraine four years into the war launched by Russia, the leaders agreed to "increase the pressure on the Russian war economy" by strengthening sanctions, including on the oil and gas sectors.

"We consider this the right moment to proceed with additional measures" now that the Strait of Hormuz is reopening in the wake of Trump's Iran deal, the statement said.

Carney said he noted a US "change in tone with respect to Ukraine", with Trump taking a harder line against Moscow and showing impatience over the casualty toll on both sides.

Trump said Monday that Russia should "make a deal", indicating Washington could re-impose waived sanctions.

- 'Real deal' -

At a lunch on Wednesday the digital sphere will take centre stage, with some European G7 members wanting more security in moves that have irked the United States.

Sam Altman, head of artificial intelligence giant OpenAI, Anthropic chief Dario Amodei, the founder of Google's AI lab DeepMind Demis Hassabis, and Arthur Mensch of their European rival Mistral AI will attend.

British Prime Minister Keir Starmer announced Monday that children under 16 would be banned from using social media in the country, with France also eyeing a similar ban.

The discussion at the G7 will focus on how to "improve cyber security and protect our children and our democracies", Macron said in an Instagram video ahead of the summit.

Trump has been the centre of attention throughout his stay at the summit in the lakeside resort of Evian.

French officials will be satisfied that the mercurial US president has stayed for the entire event and signed on to the G7 communique -- in contrast to the previous gathering in Canada, where he left early.

In an unusual gesture, Macron has invited Trump to dinner at the Palace of Versailles outside Paris after the summit winds down on Wednesday afternoon.

Trump said Tuesday that he had accepted Macron's offer of dinner because the palace of the King Louis XIV was "not gold leaf" but the "real deal".

Macron, under pressure to show he is not fawning over Trump, has already said the evening at Versailles will not be a "gala" dinner.