The Badger Trust is threatening to take the Welsh Assembly Government to court over its decision to allow a cull of badgers in Pembrokeshire.
The cull, which is planned for next spring, was authorised by Elin Jones, the WAG's rural affairs minister, in the hope of eradicating bovine tuberculosis from the area. But the trust argues that the decision was not supported by scientific evidence.
David Williams, chair of the trust, said the organisation had a constructive relationship with the WAG and had initiated the legal challenge with "great reluctance". He said the charity's decision on whether to proceed depended on the WAG's response to its solicitor's letter.
A motion to annul the cull order was heavily defeated in the Welsh Assembly last Wednesday. Williams said: "This has been a sad example of assembly members listening more to political clamour than to the science, but we remain committed to finding an acceptable alternative to culling and we are willing to enter into discussions."