Former Texas governor Rick Perry has been sworn in as Donald Trump's energy secretary – despite having once pledged to scrap the department he will now run.

The appointment was confirmed by a vote in the Senate. He was approved by 62-37.

Mr Perry has promised to protect America’s nuclear stockpile and is an advocate of all forms of US energy production, including coal and oil.

During his bid for the Republican presidential nomination in 2011, he said he planned to scrap the energy department.

But Democrats, whose votes were needed in the Senate to approve his nomination, said they had accepted Mr Perry's disavowal of that pledge.

Mr Perry will replace Ernest Moniz, who was chairman of the Massachusetts Institute of Technology physics department.

Mr Perry’s appointment will do little to assuage fears among environmentalists that the Trump administration plans to roll back Obama-era policies to limit the impact of global warming.

The new energy secretary has acknowledged that man-made climate change is real but also said combating it should not come at the expense of economic growth.

Rick Perry forgets agencies of government during debate,

“I believe some of it is naturally occurring, but some of it is also caused by man-made activity,” he said.

“The question is how do we address it in a thoughtful way that doesn’t compromise economic growth, the affordability of energy or American jobs.”

During Mr Perry's 14-years as governor, Texas was one of America’s top drillers for oil and gas.

But the state also emerged as a leading producer of wind power and a top 10 provider of solar power.

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The 66-year-old left office in 2015 and went on to launch his second bid for the Republican nomination.

He was very critical of Mr Trump, calling him a “cancer” on conservatism, but later endorsed the New York tycoon.

His confirmation came as Ben Carson was sworn in as the next secretary of the Department of Housing and Urban Development.