EDINBURGH University has conducted scientific research on more animals than any other institution in the UK, according to new figures.

A quarter of the animals used in the experiments in the UK in 2013 were tested in the laboratories of just six universities, the research shows.

Between them, the six conducted experiments on just over a million animals that year, according to information obtained by the British Union for the Abolition of Vivisection (BUAV).

Some of the animals - which included monkeys, sheep and rabbits as well as rats, mice and fish - were subjected to "distressing and disturbing" procedures, it was claimed.

However, the universities say there are strict animal welfare standards in place and the work is strictly regulated. They also pointed out the range of work had led to significant breakthroughs in conditions such as cancer, Parkinson's and multiple sclerosis.

At the top of the animal testing league was the University of Edinburgh, which used 241,865 animals in experiments.

It was followed by Oxford University (190,169), University College London (181,295), Cambridge University (169,353), King's College London (132,885) and Imperial College London (130,358).

The figures were produced in response to a Freedom of Information request made by the BUAV.

Dr Katy Taylor, head of science at the BUAV, said: "Shockingly, universities account for half of the total number of animals used in experiments carried out in the UK and are responsible for some particularly distressing and disturbing experiments.

"Yet, despite growing concern regarding animal research, much of it is publicly funded. It is ironic that many universities are also leaders in the research to find alternatives to using animals.

"So while one department may be developing cutting edge alternatives, another may be breeding animals to be used in experiments."

The experiments highlighted by the BUAV involved animals being brain damaged, injected with chemicals that cause severe disabilities, and forced to perform repetitive computer tasks.

In one anxiety experiment at Cambridge University, marmoset monkeys were said to have been blasted with loud noise and frightened with rubber snakes resembling cobras.

Other alleged procedures included subjecting young month-old rats to repeated electric shocks at Edinburgh University.

Wendy Jarrett, chief executive of the organisation Understanding Animal Research, said the six universities were the best research institutions in the UK.

"It is hardly surprising that they carry out the most animal research," she said. "We have these universities to thank for numerous medical breakthroughs over the years, from Penicillin to IVF to cancer drugs."

A spokesman for the University of Edinburgh said: "Research using animals has played and continues to play a key role in the advancement of medical, biological and veterinary science. It has made a vital contribution towards the understanding, prevention, treatment and cure of a wide range of major health problems, including cancer, heart disease and psychiatric disorders.

"The University of Edinburgh uses animals in research programmes only when their use is justified on scientific, ethical and legal grounds, and when no alternatives are available. All such work is strictly regulated and carried out under licences, which are reviewed and approved by the Home Office and are issued only if the potential benefits of the work are likely to outweigh the effects on the animals concerned.

"The university is actively involved in the development of alternative approaches that replace, reduce and refine the use of animals in research."

The BUAV approached 71 universities under the Freedom of Information Act last year and asked how many animals they had used in scientific procedures in the previous 12 months.

Details about the species used and the reasons for the testing were also requested. A total of 67 universities confirmed that they did use animals in experiments and all but three of these - Manchester, Sussex and Bristol - gave the numbers.

A Cambridge University spokesman said: "We are proud of our research, which meets the highest standards of animal welfare and is scrutinised by our Animal Welfare and Ethical Review Board - who strive to reduce the number of animals used."

A King's College London spokesman said: "Our work with animals forms part of the basis for major research breakthroughs in health and medicine, and represents a fundamental step in the search for new treatments for patients with a range of diseases including cancer, heart disease, diabetes and neurological conditions."

A spokeswoman for University College London said it was committed to a policy of "openness about animal research".

An Oxford University spokesman said: "Oxford is a pioneer in developing alternative research techniques which do not involve animals and the University only uses animals for specific and crucial elements of research which cannot be conducted in any other way."

A spokesman for Imperial College London said the use of animals in research was "vital to improve human and animal health and welfare".

Frances Rawle, from the Medical Research Council, said: "These universities all receive Medical Research Council funding for their work because we believe the high quality research they do is important and may bring about real benefit to patients in the future.

"The MRC and all the universities mentioned are looking at ways to reduce, replace or refine animal research but it is still an extremely necessary part of medical research if we are to continue to find new treatments."