Pop star Will Young has called on the puppy breeding facility MBR Acres in Wyton, Cambridgeshire, to allow laboratory dogs to be rehomed when they are no longer needed.
Actress Dame Joanna Lumley, presenter Graham Norton and Dragons Den star Deborah Meaden are among the other celebrities who have put their names to the open letter from Beagle Freedom Project UK.
The campaign group is urging MBR Acres to allow them to take animals when they are no longer required as they fear many are instead put down.
Beagle Freedom Project said it had successfully rehomed more than 3,000 dogs since it was founded in the US in 2010.
Beagle Freedom Project UK said, in its open letter signed by 40 celebrities, that consideration for the dogs' welfare "must extend beyond their time in your laboratory".
READ MORE: Campaigner glued hand to MBR Acres gates in beagle protest
"After all they have been through in their lives, we believe the dogs deserve some fresh air, a soft spot on a couch and some affection," the letter said.
"Whether that be for 10 years or a few moments.
"It is better for them to spend their last years, months, or even just days in comfort, being cared for and loved, rather than in a laboratory, alone and unknown."
Will Young, who is an ambassador for Beagle Freedom Project UK, was involved in a demonstration at MBR Acres in 2021 when he handcuffed himself to the facility's gates in protest.
READ MORE: Will Young talks about handcuffing himself to the Camp Beagle gates
Speaking to PA Media, Will said: "Beagles are the preferred choice for laboratories because of their sweet and gentle nature.
"They are docile and forgiving and do not fight back.
"The sad truth is that the very reason people love them is why they are exploited."
Robert Cogswell, director of Beagle Freedom Project UK, said: "We hope that with high-profile people agreeing to add their names to an open letter, the companies concerned will allow us to help their animals just as we have been able to do with many animal testing facilities in the US."
A spokesperson from the animal rights group Animal Rebellion spokesperson said: "We fully support the calls for dogs at the facility to be rehomed and moving towards a world where, whether it's for food, fun, or testing, that animals are no longer used by humans.
"We can build a better world where we all live in harmony."
Members of Animal Rebellion protested outside Cambridgeshire Police's headquarters in Huntingdon last year, asking police to "free" the two beagles in their care following a break-in at MBR Acres.
PA media have approached MBR Acres for a comment.
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