Professor Dylan Jones is Pro Vice-Chancellor for Biomedical and Life Sciences at Cardiff University.
He told ITV Cymru Wales that the university's animal research procedures are strictly regulated, 'certainly not cruel' and play an important part in establishing ways to alleviate human suffering.
He conceded that the institution would like to reduce the number of animals used, but said it would be 'some time' before scientists could rely solely on other methods of testing, as some remain 'unsophisticated and unreliable'.
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It will be dry for much of the night, but cloud will start to increase during the early hours of Thursday, with outbreaks of rain.