Farmers have warned that beavers are causing considerable damage on productive farmland after researchers suggested the large rodents could help restore wetlands and boost biodiversity.

A study by the University of Stirling looked at the effects of a small group of Eurasian beavers on a wetland in Tayside that was originally drained for farming.

They said that over a period of 12 years local plant richness rose by 46 per cent and the total number of plant species recorded more than doubled.

Prof Nigel Willby, of Stirling University, said wetlands were tremendously important environments for biodiversity and were disappearing at an “alarming” rate.

He added: "Beavers are renowned for their engineering skills, like dam building, and are now being considered as tools for restoring wetlands.

"They have been reintroduced widely, including in Scotland, partly for this purpose and our findings demonstrate the surprisingly large benefits they can bring to biodiversity."