Opposition to the use of animals in scientific experiments has grown significantly over the last decade, a study suggests.
Researchers analysed survey data from 2001 to 2013 in which around 1,000 US adults a year were asked if they found animal testing morally acceptable or wrong.
The results showed that last year, 41% of those questioned thought medical experiments on animals were morally wrong - 12% more than in 2001.
A more dramatic change was seen in the opinion of younger adults. Among participants aged 18 to 29, 54% were opposed to animal testing in 2013, an increase of 23% since 12 years earlier.
Women also tended to be more unhappy about animal experiments, with a majority - 52% - last year saying it was morally wrong. The number of women opposed to animal testing had risen 16% since 2001.
Just under a third of men and a third of all adults aged 30 and over were opposed to medical animal testing in 2013.
The research was presented at the annual meeting of the American Association for the Advancement of Science in Chicago.
Study author Justin Goodman, a director at Peta (People for the Ethical Treatment of Animals) and a sociology instructor at Marymount University in Virginia, US, said: "Opposition to animal testing is steadily rising among people of every gender, age group, and political affiliation, likely because people have more exposure than ever to information about the cruelty that animals endure in laboratories, how animal testing rarely helps humans, and the superior alternatives available.
"Now, the country's laws and policies governing animal experimentation and its research funding practices need to evolve to meet public expectations as well."