The Trump administration is "committed" to limiting greenhouse gas emissions, but in ways that do not threaten energy security or market competitiveness, a US official told a UN climate conference in Bonn Thursday.

The United States remains "committed to mitigating greenhouse gas emissions," said Acting Assistant Secretary of State Judith Garber.

"Our guiding principles are universal access to affordable and reliable energy, and open, competitive markets that promote efficiency and energy security, not only for the United States but around the globe," Garber said.

She said President Donald Trump still intends to withdraw from the Paris climate pact as soon as possible, but "we remain open to the possibility of rejoining at a later date under terms more favourable to the American people."

Quitting the historic, 196-nation treaty -- which will take four years -- does not mean the United States will not seek to curb the fossil fuel emissions that drive global warming, she said.

"Irrespective of our views on the Paris Agreement, the United States will continue to be a leader in clean energy and innovation," Garber told ministers and heads of state at the 12-day negotiations, which end on Friday.

Earlier in the week, Washington went against the grain of the Bonn talks by hosting a "side event" in which White House officials and US energy executives promoted the role of "cleaner fossil fuels" in curbing climate change.

"It's in the global interest to make sure that when fossil fuels are used, that it's as clean and efficient as possible," George David Banks, a special energy and environment assistant to Trump, told the event marked by protests.

US officials point to projections that major developing economies such as China and India will depend on coal and natural gas to power growth for decades to come.

At the same time, a growing body of research suggests reaching the Paris Agreement goal of capping global warming at "well under" two degrees Celsius (3.6 degrees Fahrenheit) depends on sharply curbing the use of fossil fuels, the main source of greenhouse gases.

In abandoning the Paris Agreement, Trump reneged on pledges made under the previous Obama administration to cut US carbon emissions 26-28 percent below 2005 levels by 2025.

He also said he would cut US funding to help poor countries prepare for climate change and cope with its impacts, leaving some $2.5 billion dollars pledged to the Green Climate Fund unpaid.

UN envoys are tasked with writing a "rulebook" in Bonn for the Paris Agreement, which goes into effect in 2020.

Source: AFP