The number of animal experiments carried out in the UK showed a small rise last year, despite a pledge by the government to reduce them.
Figures show 4.12 million procedures were carried out with animals, a rise of 0.3% on the previous year.
Animal welfare campaigners said the government had "broken its promise" to cut the number of tests.
The Home Office statistics show more than half of the procedures involve breeding genetically modified animals.
Overall there was a 6% increase in breeding GM animals and a 5% decrease in other procedures.
There were 3.08 million procedures on mice (75% of the total), 507,373 using fish (12%) and 226,265 with rats (6%).
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."
Michelle Thew, chief executive of campaign group the British Union for the Abolition of Vivisection, said: "The government has now failed for a third year on its 2010 post-election pledge to work to reduce the number of animals used in research.
"As a result, millions of animals continue to suffer and die in our laboratories."