Sightings of wild boar on Dartmoor have raised suspicions a guerrilla rewilder has been releasing them – and prompted a debate over whether they should be allowed to remain.

Videos of a group of boar on the moors in Devon were posted online earlier this month, and a dog walker has recently complained of a close encounter with one of them, which frightened his pet.

Experts suspect the boar could have been illegally reintroduced, possibly by people who want to repopulate the moors with the once indigenous species. Boar used to roam Dartmoor but were later hunted to extinction in Britain by the 17th century.