Badger Trust CEO Dominic Dyer told ITV News that Princess Anne is wrong to recommend the gassing of badgers.
"Princess Anne is fundamentally wrong," he said.
"Badger gassing does not work. It is very ineffective because you're pumping gas into a set with lots of tunnel entry and exit points.
"The gas does not disperse equally - it won't kill all the animals outright. On average 20-30% of them will die prolonged, long deaths or suffer brain damage as a consequence.
"So it's not effective and it also has huge humaneness issues associated with it as well."
More top news
Sarah Seawright's police photo was shared hundreds of times by fawning social media admirers after she was arrested for careless driving.
Zoo officials said the 17-year-old gorilla was killed to save the life of the boy who had crawled past a barrier into its enclosure.
Head of Germany's Protestant Church said 'extensive' Islam classes in schools could help prevent young Muslims from turning to extremism.