The 17-year-old Swede visited the 22-year-old Pakistani children's rights activist on Tuesday at the Oxford University campus where she is studying philosophy, politics and economics.

"She's the only friend I'd skip school for," wrote Yousafzai on Twitter.

She also shared a photo on Instagram of the pair sitting together on a park bench, with the caption, "Thank you @gretathunberg."

Thunberg spoke to students about "science, voting, the limits of protest, divestment, real zero v net zero, and much more", according to the college Principal Alan Rusbridger.

She posted two photos of the meeting on Twitter.

"So... today I met my role model. What else can I say? @Malala," the tweet said.

Thunberg visited Oxford on the way to the city of Bristol where she is set to join a school strike climate protest on Friday.

In 2014 Yousafzai, who was shot by the Taliban in Pakistan, became the youngest-ever recipient of the Nobel Peace Prize at 17 for her campaigning for the right to education for all children.

Thunberg was nominated and a favourite to win the award in 2019 but missed out to Ethiopian Prime Minister Abiy Ahmed.

Thunberg is in the running for the prize again this year, according to two Swedish parliamentary officials who nominated her for leading the Fridays for Future climate protest movement.

The movement has seen millions of school children around the world skipping school and demonstrate on Fridays.

Australian Associated Press