Ricky Gervais has been left "appalled" by the revelation scientists at Cardiff University sewed kittens' eyes together for an experiment.
More than 30 kittens were used in the tests - branded "sickening" by the comedian - to find out how the brain responds to sensory deprivation.
Five had their eyes sewn closed for up to a week and all of the creatures were later put down.
The Office creator told The Mirror, "I am appalled that kittens are being deprived of sight by having their eyelids sewn shut. I thought sickening experiments like these were a thing of the past."
Bosses at the university have defended the tests, which ended in 2010, insisting they were carried out in a bid to find a cure for lazy eyes in children.
A statement from the learning establishment reads, "Cardiff University rejects the accusation this experiment is cruel or unnecessary. It is impossible to use any other kind of technique for this study.
"The work was approved by both the University's ethical review process and the Home Office Animals in Science Regulation Unit as part of the licensing process."
Dominic Sullivan, Cats Protection’s Director of Legal Services, said: “We are not sure why Cardiff University used cats in this case.
"The law is quite clear, a licence cannot be granted by the Home Office to use cats in scientific experiments unless animals of no other species are suitable for the purpose of the programme. This might be the case in, say, developing a cat vaccine.
"Cats Protection hasn’t read the research but using cats in experiments for academic papers on sensory deprivation seems completely unjustifiable. It is also totally out of step with the Government’s avowed commitment to new European legislation committed to reducing the number of animals used in these type of experiments.
"There needs to be far greater transparency and openness by institutions such as the University of Cardiff who carry out these experiments - and by the Home Office when granting these licences.”
Nine ethically questionable animal experiments that made scientific history