Chinese President Xi Jinping has said he will uphold the Paris agreement on curbing climate change, in a telephone conversation with French President-elect Emmanuel Macron.

The Chinese leader's comments on Tuesday came as climate negotiators entered their second day of meetings in Bonn, Germany, aiming to start drafting a guide on how to implement the landmark deal amid fears the United States may pull out of it.

The historic accord, which came into force last year, aims to limit global temperature rise to 2 degrees Celsius above pre-industrial levels by 2100.

Most of the world's largest emitters of greenhouse gases, including China, the United States, India and the European Union, have ratified the agreement, seen as a turning point for global climate policy.

Xi told Macron that both China and France should "protect the global governance achievements contained within the Paris Agreement on climate change", according to a statement by the China's foreign ministry.

China is the world's top producer of greenhouse emissions, but support for the Paris deal was recently considered one of the few bright spots of cooperation between Beijing and Washington.

US President Donald Trump has expressed scepticism about the deal and threatened to pull out. Advisers are presenting him with a range of policy options and a final decision is not expected to be made before the G7 summit on May 26 and 27.

"It's a sign that the president wants to continue to meet with his team ... and come to a decision on what's [in] the best interest of the United States," White House press secretary Sean Spicer told reporters on Tuesday.

Many nations want Trump to remain in the agreement, which is meant to rein in rising world temperatures by shifting towards cleaner energies such as wind and solar power, even though he plans to bolster the US coal industry.

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In Bonn, where representatives of the nearly 200 countries that are party to the agreement are meeting to go through the technical aspects of implementing the accord, discussions are overshadowed by the uncertainty over Washington's position.

Al Jazeera's Dominic Kane, reporting from Bonn, said that "although there are delegates here that implement the Paris agreement in their own legislation, they very much fear what comes around the corner" from the US.

For US allies, Trump's wavering has uncomfortable echoes of President George W Bush's decision to withdraw from the 1992 Kyoto Protocol.

It could also have a negative effect on Trump's careful diplomacy with China, which the White House wants to assist with tackling North Korea's nuclear and ballistic missile programmes.

"Politically it would be a disaster; diplomatically it would be a disaster. The whole world would put the US as a pariah", Jeffrey Sachs, from the Center for Sustainable Development, told Al Jazeera.

The core of the Paris deal was an agreement between Xi and the then US president, Barack Obama. Both men have this week pressed Trump to stay on board.

The US is the world's number two producer of greenhouse gases after China.