The number of scientific testing procedures conducted on living animals increased by 6% last year, new data shows.

Across Great Britain some 3.06 million tests were carried out on animals in 2021, up from 2.88 million in 2020 – the lowest since 2004.

Data from the Home Office shows that experimental procedures (1.73 million) increased by 20% and made up 57% of all procedures last year.

Procedures for creation and breeding fell by 8%.

According to the data for England, Scotland and Wales, 96% of procedures (both for experimental and breeding purposes) used mice, fish or rats.

These species have been the most used for more than a decade.

According to the data, around half (51%) of experimental procedures were for basic research.

The top three research areas were the nervous system, the immune system and cancer (oncology).

Nic Wells, professor in translational medicine, Royal Veterinary College, and chairman of the Animals Sciences Group, Royal Society of Biology, said: “The increase in the number of animal procedures is not unexpected as the figure was particularly low in 2020 (a drop of 15% on the numbers for 2019), most likely due to the restrictions imposed by the Covid-19 pandemic.

“There has also been a rise in the number of experimental procedures compared to the number of procedures involving the breeding of genetically altered animals, particularly in the area of applied research, which may reflect a change in research priorities following the Covid pandemic.”

Some animals may be used more than once in certain circumstances so the number of procedures carried out in a year does not equal the number of animals used.

Specially protected species – cats, dogs, horses, and non-human primates – were used in 1% of experimental procedures (18,000) in 2021.

Understanding Animal Research (UAR), an organisation which promotes open communications on the issue, said animal testing is a small but important part of the research into new medicines, vaccines and treatments for humans and animals.

Ten organisations accounted for nearly half (49%) of all animal research in Britain last year.

They were the University of Oxford, University of Cambridge, UCL, the Francis Crick Institute, University of Edinburgh, the Medical Research Council, King’s College London, University of Glasgow, University of Manchester, and Imperial College London.

The UAR has also produced a list of 63 organisations in the UK that have publicly shared their 2021 animal research statistics, all of which are listed as signatories to the Concordat on Openness on Animal Research in the UK.

Wendy Jarrett, chief executive of UAR, which developed the Concordat on Openness, said: “Animal research remains a small but vital part of the quest for new medicines, vaccines and treatments for humans and animals.

“We know that the majority of the British public accepts that animals are needed for this research, but it is important that organisations that use animals in research maintain the public’s trust in them.

“By providing this level of information about the numbers of animals used, and the experience of those animals, as well as details of the medical breakthroughs that derive from this research, these Concordat signatories are helping the public to make up their own minds about how they feel about the use of animals in scientific research in Great Britain.”