Farmers' leaders are concerned about a plan to return beavers to Wales for the first time in centuries.
Wildlife experts have applied to Natural Resources Wales (NRW) for a licence to release 10 animals at an undisclosed location in south Wales this year.
But farming unions are worried about potential damage to land and crops.
NRW said it would have to consider the impact on existing wildlife and land use.
The Welsh Beaver Project said there would be a public consultation following the re-submission of the application - which was first made more than a year ago.
The group, which has previously identified the River Rheidol in Ceredigion as a preferred location to release the animals, said they can be beneficial for ecology and help with habitat restoration.
Scotland recently listed beavers as a protected species following a successful reintroduction and a pair were released on the River Otter in Devon in May to boost the genetic diversity of a group already in existence.
But Dafydd Jarrett, policy advisor for NFU Cymru, said its members needed clarity about the scheme and its potential impact on agricultural land and livestock.
"Arguably it is not necessarily a reintroduction, it is an introduction of a species," he said. "We haven't had them in Wales for many centuries now.
"We do not know really what diseases they carry and the affect to other species. There needs to be very, very careful thought before they are brought in."
Mr Jarrett added that the union had been in touch with NRW and was awaiting a date for a meeting to discuss the issues.
The Farmers' Union of Wales said more work needed to be done before beavers were reintroduced, if at all.
"Beavers can threaten property, the dams they build cause problems for migrating fish, they can damage agricultural crops and negatively affect other natural resources, not to mention flooding," a spokesman said.
"There has to be a compensation and control scheme in place and there has to be a contingency plan."