Facing populist ire at home, leaders at the G20 summit have tried to walk a fine line: acknowledge anti-globalisation anger while arguing that ever more liberal trade is the cure for sluggish economies.

"The feeling of the G20 is that if we do not address the question of fairness, it will endanger global governance as we know it," a senior European diplomat told AFP at the sprawling venue in the Chinese city of Hangzhou.

Leaders from the Group of 20 economies sought to put a gentler face on global trade, touting its benefits in lifting millions out of poverty, while acknowledging that too many had been left behind.

It was a striking tone for the Group of 20, which represents 85 percent of world GDP and two-thirds of its population.

But the declaration of inclusion and equality struck an incongruous note in a city largely deserted of ordinary people. Authorities have detained potential troublemakers and ushered away millions of citizens to make way for delegations that swept in along empty highways.

Germany's Angela Merkel best illustrated the delicate approach, calling for the system to be made fairer but also speaking out against the temptation to look inwards, with "protectionist measures that put the brakes on growth".

"The fight against inequality is an important theme, to firmly connect growth and social justice," said Merkel, whose own approval ratings have sagged after she welcomed huge numbers of refugees into Germany.

French President Francois Hollande said: "France is for globalisation but on condition that it is regulated, that there are principles, standards, particularly for the environment, for society."

- Backsliding on trade -

China's leader Xi Jinping in his opening speech warned against protectionism and backsliding on trade amid a backdrop of sluggish global growth.

But there have been mixed messages from the group's members.

US President Obama came to the summit to advocate his two signature trade deals for the European Union and Asia-Pacific. But at home his party's nominee Hillary Clinton has disowned the policies, which stand to lose her votes.

For opponents of free trade, there is no bigger target than the Transatlantic Trade and Investment Partnership (TTIP) which Washington wants to finalise before Obama steps down in January.

Activists have criticised it since negotiations began in 2013, believing it will give big business unfair benefits and allow multinationals to escape regulation through the backdoor.

Obama admitted before the G20 there was a "reaction" to globalisation and that people were "absolutely right" to worry about inequality, but insisted: "The answer is not to pull up the drawbridge."

With a note of regret echoed by other leaders at the summit, he said governments should provide better benefits and protections for workers, as "unfortunately we haven't done enough of that".

- Building walls -

China took every measure to ensure that the anti-globalisation fury on display in protests surrounding international summits over the years was absent from Hangzhou, which was put under the tightest security lockdown.

But despite the calm, the talks took place amid a perception that the global economic order exemplified by the G20 is not working for ordinary people.

Many working class citizens in developed countries believe the benefits from globalisation have flowed disproportionately to the wealthy, educated and mobile, while their own incomes have stagnated.

Canadian Prime Minister Justin Trudeau set the pace as he arrived in Hangzhou, saying leaders must push back against a tide of protectionism and nationalism.

Trudeau did not explicitly reference Donald Trump's populist campaign for the US presidency, but alluded to the Republican nominee's platform as he argued for the benefits of free trade.

"We know that building walls...does not create opportunity, growth, or benefits for the middle class."

Britain's vote to leave the European Union -- so far the most striking manifestation of the global mood -- has left it with the task of renegotiating access to the markets of the rest of the world.

New leader Theresa May sought to get a head start in Hangzhou but faced a Japanese warning over the fallout from Brexit and a lack of interest from the US -- illustrating the perils of opting out of the world's biggest economic structures.

Five things to take away from the G20 summit
Hangzhou, China (AFP) Sept 5, 2016 - This year's most exclusive and closely-watched diplomatic party -- the G20 summit -- saw presidents and prime ministers from countries representing 85 percent of the global economy gather in the Chinese city of Hangzhou.

How did the first China-hosted G20 go? While analysts correctly foresaw little prospect of big economic breakthroughs, there were some notable moments -- and notable flops.

As heads of state bid farewell to the scenic city, which authorities emptied of residents to ensure a smooth summit, here are some of the memorable takeaways.

Globalisation

Facing populist ire at home, heads of state at the G20 tried to walk a fine line by acknowledging anti-globalisation anger while arguing that ever more liberal trade was the cure for sluggish economies.

In their communique they promised to "reject protectionism" and "promote global trade".

But they also pledged to ensure that growth "serves the needs of everyone and benefits all countries and all people". It should generate "more quality jobs" address inequalities and eradicate poverty "so that no one is left behind", they said.

During the gathering leaders repeatedly admitted that many citizens feel the global trade system has failed them.

US President Obama's parting words on the G20 meeting -- his last -- were a poignant admission that these are "turbulent times" with "volatile politics" where people don't believe leadership is capable of "making sure the international economy is working for everybody".

Syria

Heading into the meeting, diplomats were hopeful that the US and Russia would reach a deal to ease fighting in Syria, but talks failed Monday despite the efforts of Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov.

The American side accused Russia of backtracking on already agreed issues which Washington refused to revisit, but the talks seemed to have been overtaken by developments on the ground, after government troops encircled rebel-held parts of Aleppo.

Maritime disputes

While China was eager to put on a show of concord in Hangzhou, tensions over the South China Sea have risen sharply, putting the Asian giant at odds with many neighbours over its expansive claims to nearly all of the strategic and resource-rich waterway.

Beijing was eager to avoid the contentious topic, but Obama took the opportunity to chide China Saturday, telling it to abide by international law, drawing a rebuke from Xi Jinping.

Japan has longstanding territorial disputes of its own with China but Xi's tone with Japanese Prime Minister Shinzo Abe was warmer than previously.

At their first meeting in over a year Xi said the two powers should "put aside disruptions" in their relationship, and Abe described China to reporters as "an important friend of Japan's since long ago".

Brexit

New British leader Theresa May came on her first prime ministerial visit to China in hopes of shaping her country's post-EU access to world markets, but faced a Japanese warning over the fallout from Brexit while the US said London was not its priority.

In the wake of its vote to leave the European Union, Britain must renegotiate its access to world markets -- a huge task for the world's fifth biggest economy.

European Commission chief Jean-Claude Juncker said he did not like the idea of Britain holding trade talks while still part of the EU.

But Britain has already had discussions on the issue with Australia, and May said after the summit that India, Mexico, South Korea and Singapore all said they would "welcome" talks on removing barriers.

US-China diplomacy

Ceremonial niceties matter at the G20, and things got off to a bad start when Barack Obama exited from the rear of Air Force One on folding stairs, a marked contrast to other leaders who descended down a large red-carpeted staircase.

But furious speculation claiming it was a deliberate snub by China, fuelled in part by a tarmac stand-off between travel press and a Chinese agent, seems to have been misplaced, as US sources told AFP the incident came about because Washington refused to use a Chinese staircase in favour of the plane's built-in steps.

Chinese authorities imposed unusually tight security on the event, with vast swaths of the city closed to normal traffic, but Obama himself downplayed the incident, leading China's nationalist Global Times newspaper to claim in a Sunday editorial that the hype was due to Western media, "which often makes a fuss over trifling issues".