The Badger Trust Cymru has written an open letter to Assembly Members urging them to block plans for a badger cull in Wales.
The plans for a cull were unveiled by rural affairs minister Elin Jones on 9 March as part of the Badger (Control Area) (Wales) 2011 order.
The assembly is due to debate the proposals on Wednesday (23 March).
Ahead of the debate, the Badger Trust has sent a letter to all AMs urging them to vote against the measures.
“This is the wrong measure at the wrong time,” said the letter. “The proposal is controversial, fraught with difficulties. Most of the badgers killed will be disease free.
“Your Assembly’s rigorous and comprehensive cattle-based measures are working. Give them more time. Everyone agrees, with TB there is no short-term fix.”
The letter claims that culling badgers is likely to increase bovine Tb in the short term and the negative publicity will be damaging to Wales.