British officials have released new numbers outlining how animals are used in experiments in UK, predictably drawing fire from animal groups.

The UK Home Office found that nearly 3.8 million scientific procedures were performed on animals in the UK in 2011 -- a 2 percent increase over 2010. The agency found that the number of cats, pigs, birds and fish used in experiments in 2011 increased by 26%, 37%, 14% and 15%, respectively. Use of rats, guinea pigs, dogs and monkeys in experiments was down, however, during the same period.

The Association of Medical Research Charities says a lot of the increase in animal procedures over the past decade can be attributed to the breeding of genetically modified animals, which is done to isolate particular genetic strains for medical research.

Numbers alone do not provide enough detail to see how how higher-welfare methods are being used to reduce suffering, the AMRC said.

The UK wing of the animal rights group PETA also argued that the numbers alone don't tell the whole story.

Statistics can't tell us what happened to the cats and other animals, and they can't reveal the suffering animals endure in laboratories. They certainly can't uncover the failings of this slipshod, outdated and ineffective approach to science, PETA UK policy advisor Alistair Currie said in an interview with the Telegraph.

A new UK law regulating animal research will take effect in January 2013. This law will require researchers to assess and record the suffering experienced by their animal test subjects.

We want the government to commit to ending severe animal suffering and for scientists to focus on changing these procedures so they cause as little pain and psychological suffering as possible, Penny Hawkins, senior scientist for the Royal Society for Prevention of Cruelty to Animals, said in a statement.

In the U.S., the federal government does not keep track of how many mice, birds and fish are used in experiments since these species are not protected by the Animal Welfare Act. The advocacy group Speaking of Research, which promotes the benefits of animal-based research, estimates that there are about 25 million of these small animals used in experiments in the U.S. every year.

Meanwhile, dogs, cats, monkeys and apes constitute less than 1% of the animals used in scientific research each year, according to Speaking of Research.

The group pointed out that the UK Home Office's definition of a 'scientific procedure' is fairly wide, including things as mild as a blood draw or breeding. They also said the increase in the use of fish reflects how important zebrafish have become in medical research, since their organ development is easily observed.

While the UK's coalition government has promised to reduce animal testing, Home Office official Martin Walsh, as quoted by  the Guardian, said this was a long-term effort.

You may be able to reduce the number of animals in specific areas, but the overall rise would tend to mask this. It's something you can't do in 12 months, Walsh said, according to the Guardian.