Donald Trump's pick for Head of Environmental Protection Agency has sued the EPA

Mr Pruitt has previously described the agency as 'unlawful and overreaching'

Donald Trump has picked Oklahoma Attorney General Scott Pruitt to head the Environmental Protection Agency(EPA) despite the fact he has led lawsuits against the federal body.

Mr Pruitt, a close ally of the oil and gas industry, has been one of the EPA's fiercest critics during Barack Obama's administration, describing it as "unlawful and overreaching".

He has attacked President Obama for allegedly trying to prevent two thirds of fossil fuels "in the ground" being used as an energy source.

Mr Pruitt has repeatedly cast doubt on climate change, saying the science behind it was “subject to considerable debate”.

As part of a coalition of state attorney generals, Mr Pruitt sued the EPA's Clean Power Plan, which aimed to reduce US greenhouse gas emissions from electricity production.

Mr Pruitt also sued the agency, again with fellow state attorney generals, over newly announced EPA regulations that seek to control the emissions of methane from the oil and gas sector.

On announcing his decision, Donald Trump said: "For too long, the Environmental Protection Agency has spent taxpayer dollars on an out-of-control anti-energy agenda that has destroyed millions of jobs, while also undermining our incredible farmers and many other businesses and industries at every turn.

He said the Oklahoma attorney general "will reverse this trend and restore the EPA’s essential mission of keeping our air and our water clean and safe".

"My administration strongly believes in environmental protection, and Scott Pruitt will be a powerful advocate for that mission while promoting jobs, safety and opportunity", he added.

The President-elect's own statements on climate change during the campaign have caused consternation and worry among environmentalists, seeing him describe global warming as "a hoax" that was "invented by and for the Chinese".

After he won the election in November, the billionaire businessman did appear to undergo an U-turn on the issue when he admitted in a news conference "there was some connectivity" between human activity and climate change.

There are ongoing fears Mr Trump would follow through with his previosuly stated objective of preventing the US signing up to the Paris climate change agreement.