Guardian Media Group has banned all advertising from oil and gas companies in a move applauded by teen climate activist Greta Thunberg.

The group said the decision may make its short-term future “a tiny bit tougher” financially, but that it is hoping some brands will be impressed by the stance and choose to work with it more as a result.

The ban, which began with immediate effect yesterday, will extend to the Guardian, Observer and Guardian Weekly in print as well as the Guardian’s website and news apps.