Thunberg, 16, has encouraged students to skip school to join protests demanding faster action on climate change, a movement that spread far beyond Sweden.

On Friday, about 40,000 students in Australia are expected to strike in as many as 55 separate protests as part of the School Strike 4 Climate campaign. That number is about twice that of a similar action in November, with over 100 nations likely to take part this time around.

Thunberg has been staging a Friday strike since last year, boycotting 42 days of classes since she began last year.

"The plan was to school strike for three weeks [in the run up to Swedish elections]," she said. "But at the end of that I wanted to go on. So then I started Fridays For Future ... The emissions are still going up so nothing has been achieved really."

When not standing vigil in public protests, the 16-year-old has travelled widely - always avoiding flights to save on greenhouse gas emissions - and addressed a UN conference on climate in Poland, the World Economic Forum in Davos and the European Union in Brussels, among other events.

"But my grades are still good and I have not missed out on what I need to achieve in school," she said.

Any national lawmaker can nominate somebody for the Nobel Peace Prize.

The Norwegian Nobel Committee doesn't publicly comment on nominations, which for 2019 had to be submitted by February 1.

Friday's strike will be held from midday at the Sydney Town Hall, the Old Treasury in Melbourne and Garema Place in Canberra. In Brisbane it will be held from 1pm at Queen's Gardens and in Perth from 11am at St George's Cathedral, with dozens of other protests to be held in regional parts of Australia.

AP with Peter Hannam