Sharp rise of 8% in UK animal experiments
The number of animal experiments carried out in the UK rose by 8% in 2012, according to Home Office figures.
The rise is due to a growth in the use of genetically modified (GM) animals.
According to the way the Home Office classifies statistics, procedures on GM animals were higher than the number on non-GM animals for the first time.
Campaigners criticised what they said was the government's failure to deliver on a post-election pledge to cut the number of procedures.
About 4.11 million scientific experiments on animals took place in 2012, an increase of 317,200 on the previous year.
The number of GM animals increased by 22%; this year saw 1.91 million genetically modified animals used compared to 1.68 million non-GM animals.
Mice were the most frequent animals used, accounting for about three-quarters, or 1.98 million procedures.
After mice, rats and fish were the most common species used. There was also a 22% increase in the use of non-human primates such as Old World Monkeys, a group which includes macaques and baboons.
The number of procedures involving animals with harmful genetic mutations rose by 13%, with mutant mice accounting for the majority.
The government report said: "The overall level of scientific procedures is determined by a number of factors, including the economic climate and global trends in scientific endeavour.
"In recent years, while many types of research have declined or even ended, the advent of modern scientific techniques has opened up new research areas, with genetically modified animals, mainly mice, often being required to support these areas."
Lord Taylor, minister for criminal information, said that the government "provides a commitment to work to reduce the use of animals in scientific research" which is "an ambitious but achievable goal".
He added: "We recognise that the use of animals in scientific research is a small but essential function in improving our understanding of medical and physiological conditions, the research and development of new medicines and the development of leading edge medical technologies and is necessary to ensure the safety of our environment."
In 2010, the coalition government pledged to promote higher standards of animal welfare.
They stated: "We will end the testing of household products on animals and work to reduce the use of animals in scientific research."
Referring to this pledge, the British Union for the Abolition of Vivisection (Buav) said the continued rise in testing amounted to "a broken promise".
Michelle Thew, chief executive of Buav, commented: "The government has failed for a third year on its post-election pledge to work to reduce the number of animal experiments and, as a result, millions of animals continue to suffer and die in our laboratories.
"This lack of progress is completely unacceptable. We need to see meaningful and lasting changes for animals in laboratories."
Dominic Wells from the Royal Veterinary College said: "We are in an era of developing treatments for rare diseases in a way that we could not have predicted five years ago. We are the victims of our own success and this has inevitably led to the use of more animals."
Dr Ted Bianco, acting director of the Wellcome Trust, said that the scientific community is deeply committed to reducing the numbers of animals used in research, but despite significant progress, "animals remain an essential part of helping us understand disease and develop much-needed new treatments".
"This year's increase reflects the use of powerful techniques to help us model with greater accuracy human disease. In particular, the inclusion of genetically modified mice, whose breeding alone counts as a procedure, is largely behind this increase, but will ultimately allow us to reduce the number of animals used."