The British contingent of People for the Ethical Treatment of Animals (PETA UK) and its German affiliate have called for an end to the Danish military's animal-based trauma training, in which live pigs are shot and blown up.
The campaign groups released graphic never-before-seen photographs of the training exercise slaughter, in their appeal to the Danish Minister of Defence, Nicolai Wammen.
The disturbing images show live pigs hanging from a wooden frame and shot with rifles and handguns to inflict traumatic injuries, after which military personnel operate on and kill the animals.
In a letter penned to Wammen, the groups point out that over 80% of NATO allies have already ended the cruel use of animals in the military exercises.
Instead of shooting, stabbing and blowing up the animals, military personnel in the nations are trained to treat traumatic injuries using life-like human simulators.
The Caesor military simulator is used by the NATO Centre of Excellence for Military Medicine, as well as other methods that avoid harm to animals. The technology has proved to be more successful in military and civilian studies to teach life-saving skills, over the previous use of animal laboratories.
According to the European Union's Directive 2010/63/EU and Denmark's Animal Welfare Act, non-animal methods are to be used to train the military whenever available.
Maiming animals in this way is not permitted in Britain under the Animals (Scientific Procedures) Act 1986.
However, the UK military still participate in this biennial training, which is part of the Danish surgical training course informally known in military circles as "Danish Bacon".
Mimi Bekhechi, associate director at PETA UK, said: "Clearly, if 23 NATO nations (20 of which are EU member states) can train medical personnel without the use of animals, the Danish and British armed forces can and must do so too."
Bekhechi added: "The UK government's decision to ship out members of the armed forces for deadly and cruel exercises in Denmark - which would be illegal if conducted in the UK - is impossible to justify medically, ethically or educationally."
According to PETA, the British Army sends surgeons to Jaegerspris Kaserne in Denmark twice a year, to take part training in which pigs are "subjected to bullet and blast wounds".
The group has previously appealed to the UK MoD to end its participation in these crude exercises, while filing a complaint with the European Commission against Denmark.
Following discussions with PETA and PETA US, the Polish military replaced its animal laboratories with simulation technology.