The Prime Minister, who faces a row with Beijing over the delayed decision on the Hinkley Point power station, maintained that it was a “golden era” for UK-China relations.
Speaking at Heathrow before boarding an RAF plane to Hangzhou, eastern China, she said: “The message for the G20 is that Britain is open for business. As a bold, confident, outward-looking country we will be playing a key role on the world stage.”
Ahead of talks with Chinese president Xi Jinping, she added: “This is a golden era for UK-China relations and one of the things I will be doing at the G20 is obviously talking to president Xi about how we can develop the strategic partnership that we have between the UK and China.
“But I will also be talking to other world leaders about how we can develop free trade around the world, and Britain wants to seize those opportunities.
“My ambition is that Britain will be a global leader in free trade.
“I will be talking to other world leaders about the opportunities for trade around the globe that will open up for Britain following Brexit.”
The Prime Minister hopes to use the G20 summit, where she will hold talks with world leaders including US president Barack Obama, to show that the UK remains a “dependable” diplomatic and trading partner in the wake of the vote to quit the EU.
But despite holding face-to-face talks with the Chinese president, 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.
She will have a meeting with president Xi tomorrow, after the conclusion of the two-day G20 summit of leaders of the world’s richest nations.
During the summit, 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.
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.