Thousands of students are gathering in the German capital, skipping school to take part in a rally demanding action against climate change.

Swedish teenager Greta Thunberg, who inspired the protests in Germany and elsewhere by staging weekly "school strikes," is expected to lead the Friday rally through Berlin's government district.

The 16-year-old is also meeting with scientists at the Potsdam Institute for Climate Impact Research, just outside the German capital.

The weekly "Fridays for Future" protests have been largely welcomed by German politicians, though some have criticized students for protesting during school time.

One placard at the protest read: "I'll go to school if you keep the planet cool."

Chancellor Angela Merkel has called the protests "a very good initiative."