Ex-Im said late last week that it would make exceptions for countries without any other options that were financially feasible, or in cases where a plant already had carbon capture technology.

“No one has been more supportive of US exports and the American jobs they produce and maintain than this bank and this board,” firm chairman and president Fred Hochberg said, noting it had supported about 1.2 million jobs since 2009.

“We can't do it, however, without considering the environmental costs associated with transactions."

Ex-Im officials said the revisions to the policy were drafted by its staff, then reviewed at length by exporters, the administration, the public, leading environmental groups and other federal agencies.

The move follows criticism from the environmental community for its $US9.6 billion in loans to fossil fuel projects last year, bypassing its policy on greenhouse gas emission considerations.

“The bank engages in an important balancing act – in supporting our exporters, we have to weigh the potential impacts on the environment associated with our financing," Hochberg said.

“This balancing act is a Congressional mandate, is a directive in our charter, is part of our mission and it is something we at the bank take seriously.”

The revisions, Ex-IM said, would balance its obligations to stakeholders while supporting the growth of export-related US jobs.

“Without guidelines or limits, ever-increasing numbers of new coal plants worldwide will just continue to emit more carbon pollution into the air we breathe," Hochberg said.

“But America cannot do this alone. I strongly support the administration's efforts to build an international consensus such that other nations follow our lead in restricting financing of new coal-fired power plants.”