Donald Trump’s treasury secretary has followed the US president in taking a swipe at Greta Thunberg, suggesting the teenage climate activist should study economics at university before she offers advice on how to tackle global warming.

Steven Mnuchin questioned the 17-year-old Swede’s credentials after she called for public and private sectors to divest from fossil fuels.

Speaking at the Davos summit on Thursday, Mr Mnuchin said: “Is she the chief economist? Who is she? I’m confused.”

“After she goes and studies economics in college, she can come back and explain that to us.”

Ms Thunberg – who has taken a year out of school to campaign globally for climate action – responded in a tweet: “My gap year ends in August, but it doesn’t take a college degree in economics to realise that our remaining 1,5° carbon budget and ongoing fossil fuel subsidies and investments don’t add up.

“So either you tell us how to achieve this mitigation or explain to future generations and those already affected by the climate emergency why we should abandon our climate commitments.”

Mr Mnuchin’s comments in the Swiss resort came after the teenage activist and the president clashed over the Trump administration’s climate record at the World Economic Forum earlier this week.

Ms Thunberg has been an outspoken critic of the US government’s “inaction” over global warming, and said in Davos that the president was “fuelling the flames” of the climate crisis.

Mr Trump criticised the teenager’s “pessimism”, made remarks about her age, and accused environmental campaigners of being “prophets of doom”.

The president was been widely criticised for his decision to pull the US out of the Paris climate change agreement, but his treasury secretary told a press briefing in Switzerland on Thursday the move had been misinterpreted.

He claimed the president, who has repeatedly described manmade climate change as a hoax, “absolutely believes” in environmentalism.

“What the president objects to is the Paris agreement, because he thought it was an unfair agreement for the United States,” he added.

Mr Mnuchin’s remarks about Ms Thunberg were described as “patronising” and “smug” by commentators on social media.

Author and climate activist Naomi Klein tweeted: “Somebody should tell Mnuchin about the hundreds of Harvard faculty members — and thousands at other universities — who have called for fossil fuel divestment too.”

Questioned about his comments in a later interview with CNBC, the treasury secretary said he had “nothing against the climate issue” but added: “I think that the youth needs to understand climate is one issue that needs to be put into context with lots of other things”.

“This is not the doom and gloom issue that is going to impact everybody over the next 10 years. It is an issue that should be considered along with a lot of important issues.”

The US government was “much more focused on Iran not having nuclear weapons,” he said.

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