Barack Obama has railed against US political and business figures who oppose the expansion of wind and solar power in a speech where he singled out the influential Koch brothers for criticism.

Accusing opponents of his energy policies of "wanting to protect an outdated status quo" based on fossil fuels, he warned them away from "standing in the way of the future" and his efforts to combat climate change.

Obama delivered the closing address at the eighth National Clean Energy Summit in Las Vegas, co-sponsored by Senator Harry Reid of Nevada. The senate minority leader had 24 hours earlier given a forceful endorsement of Obama's nuclear deal with Iran and as the president took the podium on Monday he acknowledged Reid's boost to his efforts to prevent Congress from blocking the international pact.

Obama said: "I want to thank him for his statement over the weekend in support of a deal that makes sure Iran does not get a nuclear weapon. The deal is a historic diplomatic breakthrough, the best of American foreign policy."