But despite holding face-to-face talks with Chinese president Xi Jinping, Mrs May is not expected to use the meeting to make an announcement on the Hinkley Point project, which is backed by Beijing’s state-owned nuclear firm, The Press Association reported.
Mrs May will have a meeting with president Xi on Monday, after the conclusion of the two-day G20 summit of leaders of the world’s richest nations in Hangzhou.
Although a decision on whether or not the Hinkley Point C project in Somerset will go ahead is expected this month, UK officials indicated it would not be announced at the meeting with the Chinese leader – fuelling speculation the plan will be scrapped or significantly altered.
“We have set out the Government’s approach to Hinkley, we are currently considering all the component parts of that,” a UK source said.
“We have said we will make a decision this month, that remains the plan. I don’t expect one in the next few days and I don’t expect our Chinese or French partners are expecting one in the next few days.”
The French energy giant EDF, with support from China General Nuclear, had expected to build the £18 billion plant, but in a surprise move Mrs May’s administration signalled a delay in making a final decision on the project amid reports of security concerns about Beijing’s involvement and the high cost of energy from the power station.
With the UK seeking a new role on the world stage following the Brexit vote, the decision on Hinkley Point has major diplomatic implications for relations between the UK, France and China.
But UK officials insisted the country’s status in the world would not be affected by Hinkley Point, whatever Mrs May decides to do.
“I’m not sure that, when you look around the world and all the UK’s partners, that we are defined by one energy project,” the source said.
China’s ambassador to the UK Liu Xiaoming has urged Britain to “continue to be pragmatic and stay open to Chinese businesses” after the Brexit vote.
In an article for the state-run China Daily on Thursday, Mr Liu made no direct reference to Hinkley, but said “a number of steps need to be taken in order to maintain the momentum in the relationship” between London and Beijing.
The GMB union, which supports the Hinkley Point project, said the G20 summit was “High Noon” for the scheme – but it was not yet clear whether Mrs May would be the hero or the villain.
The union’s Justin Bowden said: “The UK Government must be hard-headed in pursuit of the national interest, at the same time as not abandoning their commitment, with other parties, to secure a low-carbon and affordable energy future.”
During the summit, Mrs May will hold her first face-to-face talks with Russian leader Vladimir Putin, and is expected to adopt an approach of “hard-headed engagement” with Moscow.
She will also have a meeting with her Indian counterpart Narendra Modi, with the trading relationship expected to dominate the agenda.
Mrs May’s talks with president Obama follow the US leader’s warning that the UK would be at “the back of the queue” for a trade deal if it voted to leave the EU.
But amid reports the planned US-EU trade deal has stalled, the UK hopes for talks on a transatlantic agreement of its own with Washington.
Officials said the talks would “explore how does that relationship look once the UK leaves the EU”.
During the summit, Mrs May will have the chance to mingle with world leaders – including during a boat trip on Hangzhou’s lake – for the first time since the EU referendum.
“It is a real opportunity for the Prime Minister to send a clear message to the world’s biggest economies that Britain will continue to play a bold, confident and outward-looking role as the UK leaves the EU,” a source said.
Mrs May wants to show that the UK remains “open for business, that we will continue to be a strong and dependable partner”.
She will make an intervention during a summit session to set out how she sees the UK’s role and her desire for a “smooth and orderly departure from the EU and stronger trading relations in the future”.
The Prime Minister also wants to push for action on tackling terrorism – including stopping the flow of money and foreign fighters to extremist groups such as Islamic State (IS).
She will also press for action to make sure that as IS is forced out of strongholds, including in Libya, the group’s fighters are not able to find new safe havens in areas such as sub-Saharan Africa.