London, Dec 5 (IANS): British broadcaster Jeremy Clarkson has called 16-year-old climate activist Greta Thunberg "mad, dangerous", adding that she should "go back to school and shut up", a media report said on Thursday.

Clarkson spoke out against the Swedish eco-warrior while promoting the latest season of motoring series "Grand Tour" on an Australian chat show on Thursday morning, The Daily Mail said in the report.

The broadcaster, who has been an outspoken critic of global warming, admitted that he has had a change of heart after shooting the series in Southeast Asia.

But when asked about Thunberg, the television presenter made it clear that he was still not a fan of the climate change campaigner.

"She's mad and she's dangerous and she's causing young children sleepless nights with her idiocy," he said.

"I think she needs to go back to school and shut up."

Clarkson's comments on Thursday came days after he fired shots at Thunberg during an interview with The Independent newspaper in which he branded her a "stupid idiot".

Clarkson, who regularly calls out the activist on social media and in his column with The Sun, also accused her of being a hypocrite.