The Coalition of Badger Action Groups encouraged visitors to the website to “spend a few minutes contacting these people and let them know your views on the badger cull”, adding that the group was planning protests outside the businesses.
The group said they had been told by the government that the organisers of the cull would be kept secret for security purposes, but that simple research had uncovered the names.
The NFU expressed concern over the leak and said that it was seeking reassurance from Defra and Natural England about the security of their systems.
NFU director of policy Martin Haworth said: “We are very disappointed that this has happened and we are doing everything we can to support and protect those individuals that have been named.
“We have asked Defra and Natural England how this information could have been discovered and to carry out their own investigations. They have come back to us and confirmed that both of their systems are secure.”