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.”

Davos 2020 - in pictures Show all 14 1 /14 Davos 2020 - in pictures Davos 2020 - in pictures U.S. President Donald Trump walks out of the Marine One helicopter as he arrives for the 50th World Economic Forum (WEF) in Davos, Switzerland, January 21, 2020 REUTERS Davos 2020 - in pictures Spotters gather on a viewpoint to take pictures of Air Force One (not pictured), carrying US President Donald J. Donald Trump, as it lands at Zurich Airport, Switzerland, 21 January 2020. Trump arrived in Switzerland to attend the 50th annual meeting of the World Economic Forum (WEF) in Davos EPA Davos 2020 - in pictures U.S. President Donald Trump waves as he arrives for the 50th World Economic Forum (WEF) in Davos, Switzerland, January 21, 2020 REUTERS Davos 2020 - in pictures A Secret Service agent takes a photo as the Marine One helicopter carrying U.S. President Donald Trump flies nearby en route to the Word Economic Forum in Davos, Switzerland January 21, 2020 REUTERS Davos 2020 - in pictures US President Donald J. Trump smiles before addressing a plenary session during the 50th annual meeting of the World Economic Forum (WEF) in Davos, Switzerland, 21 January 2020. The meeting brings together entrepreneurs, scientists, corporate and political leaders in Davos under the topic 'Stakeholders for a Cohesive and Sustainable World' from 21 to 24 January 2020 EPA Davos 2020 - in pictures Ivanka Trump, special adviser to the president and senior advisor Jared Kushner listen as U.S. President Donald Trump delivers a speech during the 50th World Economic Forum (WEF) annual meeting in Davos, Switzerland, January 21, 2020 REUTERS Davos 2020 - in pictures Artists from Fete des Vignerons perform a song "Ranz des Vaches" before U.S. President Donald Trump's speech during the 50th World Economic Forum (WEF) annual meeting in Davos, Switzerland, January 21, 2020 REUTERS Davos 2020 - in pictures US President Donald J. Trump (R, red tie) walks in the Congress Centre after addressing a plenary session during the 50th annual meeting of the World Economic Forum (WEF) in Davos, Switzerland, 21 January 2020. The meeting brings together entrepreneurs, scientists, corporate and political leaders in Davos under the topic 'Stakeholders for a Cohesive and Sustainable World' from 21 to 24 January 2020 EPA Davos 2020 - in pictures Swedish climate activist Greta Thunberg addresses a panel session during the 50th annual meeting of the World Economic Forum (WEF) in Davos, Switzerland, 21 January 2020. The meeting brings together entrepreneurs, scientists, corporate and political leaders in Davos under the topic 'Stakeholders for a Cohesive and Sustainable World' from 21 to 24 January 2020 EPA Davos 2020 - in pictures Swedish environmental activist Greta Thunberg (C) listens to a speech by US President Donald J. Trump at a plenary session during the 50th annual meeting of the World Economic Forum (WEF) in Davos, Switzerland, 21 January 2020. The meeting brings together entrepreneurs, scientists, corporate and political leaders in Davos under the topic 'Stakeholders for a Cohesive and Sustainable World' from 21 to 24 January 2020 EPA Davos 2020 - in pictures U.S. President Donald Trump speaks dutring a bilateral meeting with European Commission President Ursula von der Leyen during the 50th World Economic Forum (WEF) annual meeting in Davos, Switzerland, January 21, 2020 REUTERS Davos 2020 - in pictures Demonstration organized by Juso Schweiz (Young Socialist Party) on the sideline of the 50th annual meeting of the World Economic Forum, WEF, in Davos, Switzerland, 21 January 2020. The meeting brings together enterpreneurs, scientists, chief executive and political leaders in Davos January 21 to 24 EPA Davos 2020 - in pictures Governor of the Bank of England Mark Carney attends a session at the 50th World Economic Forum (WEF) annual meeting in Davos, Switzerland, January 21, 202 Reuters Davos 2020 - in pictures U.S. President Donald Trump shakes hands with the President of the Swiss Confederation Simonetta Sommaruga during a bilateral meeting at the 50th World Economic Forum (WEF) annual meeting in Davos, Switzerland REUTERS

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.”