The number of experiments carried out on animals in UK laboratories has continued to rise, statistics show.
The majority of testing involves rodents
The number of procedures undertaken in 2005 was just under 2.9 million, a rise of about 1.4% on the previous year, according to the Home Office figures.
The majority involved mice, rats and other rodents; most of the remainder were carried out on fish and birds.
Non-human primates, dogs, cats and horses were used in less than 1% of scientific procedures in 2005.
But the number of procedures using non-human primates was up 11% on 2004.
The figures still represent a significant reduction on what was happening in the 1970s.
"Animal research and testing has played a part in almost every medical breakthrough of the last century. It has saved hundreds of millions of lives worldwide, and is vital to our NHS," said Home Office Minister Joan Ryan.
"Where animal research is the only option, we will continue to ensure that the balance between animal welfare and scientific advancement is maintained."
Mice, rats and other rodents were used in 85% of procedures in 2005. Fish were used in 8% of procedures and birds in 4% of tests.
The number of procedures using non-human primates was 4,650, up 11% from 2004. The number of animals used for these procedures was up 12% on 2004.
The Home Office report says this was largely due to the use of macaques in drug safety and effectiveness trials.
In total, 2.8 million animals were used in procedures last year.
Between 1974 and 1996, the number of procedures on animals fell year on year. But since 2000, the number of tests has been rising by an average of 1-2% per year. This trend is in large part due to the use of genetically-modified animals.
By adding or knocking out genes in mice, scientists believe they can gain an insight into the molecular flaws in humans that lead to illness.
The numbers of tests involving normal animals has been falling steadily since 1995.
But animal welfare groups are worried that the downward trend in overall procedures that started in the 1970s is showing signs of a significant reverse.
Alistair Currie, campaign director for the British Union for the Abolition of Vivisection (Buav), commented: "Sadly, it's no surprise that numbers have gone up again. This government has no grasp of the problem of animal experimentation and no strategy to bring numbers down.
"This is yet another example of Home Office failure: they have shown that they are no more 'fit for purpose' in regulating animal experiments than they appear to be in crime, illegal immigration, prisons and everything else they are responsible for."
In 2004, the government established a National Centre for the Replacement, Refinement and Reduction of Animals in Research.
The so-called 3 "R's" are supposed to underpin laboratory rules and culture. They emphasise the need to reduce suffering and find replacement methods that do not involve animals.