President-elect Donald Trump has formally announced Rick Perry, a former Texas governor and Mr Trump’s one-time presidential rival, as his choice to lead the US Department of Energy.

If the nomination is confirmed by the Senate, the move would put Mr Perry in charge of a federal department that he had proposed eliminating during his bid for the 2012 Republican presidential nomination.

The choice adds to the list of oil drilling advocates sceptical about climate change who have been picked for senior positions in Mr Trump’s Cabinet. The selections have worried environmentalists but cheered an industry eager for expansion.

Meanwhile, US media are reporting that the Department of Energy has refused to answer questions issued to them by Mr Trump’s transition team.

The Trump team has reportedly asked officials to name department employees who had worked on international climate agreements and initiatives to cut carbon emissions.

Some media have referred to the move as a “witch hunt”, particularly given that Mr Trump has formerly called global warming a “hoax”.

Department officials reportedly described the questions as “intrusive” and hinted that the Trump team may target specific people.

“It is a remarkably aggressive and antagonistic tone to take with an agency that you’re about to try to manage,” an employee told Politico.

The Energy Department is responsible for US energy policy and oversees the nation’s nuclear weapons program.

Mr Perry served as governor of Texas, a leading oil-producing state, from 2000 when he succeeded President George W Bush until 2015.

Mr Perry was a fierce critic of Trump last year before dropping out of the race, calling him “a cancer on conservatism” who offered “a toxic mix of demagoguery and mean-spiritedness and nonsense.”

Mr Trump also had harsh things to say about Mr Perry during the campaign, even belittling his eye glasses by saying: “He put on glasses so people will think he’s smart.”

Once Mr Trump secured the nomination, Mr Perry endorsed him as “the people’s choice.”

Rick Perry’s ooops moment at 2001 presidential debate

Mr Perry has advocated lighter regulation on the fossil-fuel industry, and has said that the science around climate change is “unsettled.”

– with agencies