Beavers should be released across the country under a Labour government, Sadiq Khan has said. The London mayor said he was disappointed with recent comments by the environment secretary, Thérèse Coffey, who said her department would not be legalising beaver releases as she had “other priorities”. At the moment, beavers can only be legally released into large enclosures, not into the wild. There are some living free in parts of the UK, including Devon, and there is a large population in Scotland – there largely as a result of escapes from private collections and illegal releases. Beavers have been also released under licence in Scotland to bolster wild local beaver populations, and last year Nature Scot, Scotland’s nature agency, published a plan for a widespread return of beaver to the country. It is unclear whether a future Labour government would legalise beaver releases into the wild. Sources say the shadow Department for Environment, Food and Rural Affairs (Defra) team is still writing its nature manifesto. Beavers once lived in the UK in large numbers, but were hunted to extinction 400 years ago for their fur and an oil they produce. With their dams, they create wetlands that are important for biodiversity – one study found that wild-living beavers have alleviated flooding, reduced pollution and boosted fish populations. Beavers are loved by wildlife campaigners who call them “nature’s gardeners”. “I was disappointed when I heard Thérèse Coffey say what she said recently in relation to her lack of priorities to rewilding. I’m disappointed that they’re not bringing beavers back,” the mayor told the Guardian. “They know the evidence about beavers, helping protect ecosystems, and one of the points I’m saying to the Labour team nationally, is not only is this the right thing to do for our environment, for our communities, it is a vote-winner – a no-brainer.” Earlier this month, Khan released two beaver kits into the Paradise Fields nature reserve in Ealing, west London. Though they will remain in an enclosure, he hopes they can improve biodiversity there and bring locals closer to nature. “The first cage was the mother being let out and you could see the cage moving and I did get a bit scared, I’ve got to be honest,” Khan said of his experience with the beavers. “But when the mother went out she was a joy to watch and the two kits, when they got out of my cage, once they were in the water, they were swimming around, and one of them was proper posing. I named her Taylor Swift because she was dancing around, she was having a great time. “I challenge you not to smile, when you see these beavers swimming around, in that lovely park in Ealing, and I want other people to enjoy just watching wildlife and having a smile.” Khan is enthusiastic about nature and rewilding and has launched a multimillion pound plan to improve London’s green spaces for nature, and add new ones. It was not just a good way to decarbonise the city, he said – it was also a social justice issue to bring nature closer to people. Khan also believes strong rewilding policies would be a vote-winner for Labour. He said: “What’s exciting is you can … say to people, listen, we’re the party bringing forward policies to rewild, to have more greenery, it gives you another reason to vote for us in the next general election.”