Teen climate activist Greta Thunberg said on Tuesday that while self-isolating after recent travels in Europe she probably came down with COVID-19, and urged other young people to stay at home too if even just a little unwell, to help stop the coronavirus.

Swedish Thunberg said on Instagram she had now recovered from symptoms milder than her latest cold, and may not have suspected COVID-19 had it not been for her father, who had travelled with her, developing more severe symptoms.

"Many (especially young people) might not notice any symptoms at all, or very mild symptoms. Then they don’t know they have the virus and can pass it on to people in risk groups," she said.

"We who don’t belong to a risk group have an enormous responsibility, our actions can be the difference between life and death for many others. Please keep that in mind, follow the advice from experts and your local authorities and #StayAtHome to slow the spread of the virus."

The founder of the Fridays for Future youth movement said she had not been tested for the virus but given the combined symptoms and circumstances it was very likely she had it. She had self isolated because she had visited countries hit by coronavirus infection.

Fridays for Future calls on politicians to listen to climate scientists and take urgent action to against global warming.