Speaking on the last day of an IEA ministerial meeting in Paris, Wright said the 52-year-old agency should return to its founding mission of ensuring energy security.

The IEA was created to coordinate responses to major disruptions of supplies after the 1973 oil crisis, but Wright complained that it had adopted a climate agenda that includes the goal of reaching net-zero emissions by 2050.

"The US will use all the pressure we have to get the IEA to eventually, in the next year or so, move away from this agenda," Wright said in a news conference, calling net zero a "destructive illusion".

"But if the IEA is not able to bring itself back to focusing on the mission of energy honesty, energy access and energy security, then sadly we would become an ex-member of the IEA," he added.

The net-zero emissions target is crucial to meet the Paris climate agreement's goal of limiting global warming to 1.5C from pre-industrial levels.

But Wright, a former fracking executive, said there was a "0.0 percent chance" that net zero would be achieved.

- US 'undecided' over IEA leadership -

The IEA produces monthly reports on oil demand and supply as well as annual world energy outlooks that include data on the growth of solar and wind energy, among other analyses.

Wright praised IEA chief Fatih Birol for reinserting in last November's annual outlook a Current Policies Scenario in which oil and gas demand would grow in the next decades. That scenario had been dropped for the past five years.

But the report still included a scenario where the world reaches net-zero emissions by mid-century.

Birol's current four-year term ends next year but Wright demured when asked who he would like to head the IEA, which has over 30 member nations.

"We remain today undecided or neutral on who the leadership is. We care about the mission much more than the individual leaders," the US energy chief said.

If Birol can make the agency "get out the politics and get out the anti-energy part of it, that's great by us", said Wright, who first warned last year that the US could leave the IEA if it did not reform.

Birol told ministers on Wednesday that the IEA was a "data-driven" and "nonpolitical organisation".

In a sign that not all nations agree with Wright, British energy secretary Ed Miliband announced Wednesday that the UK would contribute a further 12 million pounds ($16 million) to the IEA's Clean Energy Transitions Programme.

"The age of electricity is unstoppable," Miliband said.