WASHINGTON - US President Donald Trump on Tuesday signed an executive order aimed at reversing his predecessor Barack Obama's climate policies.

Trump, who once called climate change a "hoax". signed the Energy Independence Executive Order, during his first visit to the US Environmental Protection Agency (EPA).

Flanked by coal miners invited to attend the signing, the president hailed the order as "the start of a new era" in American energy production that would put an end to the "war on coal".

"With today's executive action, I am taking historic steps to lift the restrictions on American energy, to reverse government intrusion and to cancel job-killing regulations," Trump said.

The main target of the order is the so-called Clean Power Plan, a signature effort by Obama to reduce greenhouse gas emissions from coal-fired power plants in keeping with promises of the 2015 landmark global climate deal known as Paris Agreement.

The order asked the EPA to initiate a process to review and rewrite the Obama-era rule, which actually has been put on hold by the US Supreme Court in February 2016.

The decree also sought to overturn limits on coal leasing on public lands, methane emissions from oil and gas production, and requirements to include climate change as part of environmental assessments, as well as reexamine the social cost of greenhouse gases.

The room was filled with miners, coal company executives and staff from industry groups, who applauded loudly as Trump spoke. Shares in US coal companies edged higher in response.

The wide-ranging order is the boldest yet in Trump's broader push to cut environmental regulation to revive the drilling and mining industries, a promise he made repeatedly during the 2016 presidential campaign.

"I cannot tell you how many jobs the executive order is going to create, but I can tell you that it provides confidence in this administration's commitment to the coal industry," Kentucky Coal Association president Tyler White told Reuters.