Qantas has put the kybosh on online activist group GetUp's latest anti-censorship campaign, refusing to run the "Censordyne" ad on its flights.

Simon Sheikh, chief executive of GetUp, said the group had planned to run the parody ad on all Qantas domestic flights into Canberra next month to ensure it was seen by politicians and their staff members around the first sitting week of Parliament.

But Qantas refused to run the ad, which lampoons the Government's forthcoming internet filtering scheme, saying it had a long-standing policy not to run "political advertising".

Meanwhile, GlaxoSmithKline, which owns the Sensodyne brand, on which the parody campaign is based, said it was considering legal action against GetUp.