Compassion is being joined by the World Society for the Protection of Animals (WSPA) in contesting controversial plans for a 1,000-cow mega-dairy in Powys after Councillors recently conditionally approved them.
The council's approval came despite a recommendation from their own planning officials to reject the proposal.
Powys planners advised that the mega-dairy 'fundamentally conflicts' with at least nine policies of the Powys Unitary Development Plan.
Compassion and WSPA have written to the Welsh Assembly, asking them to call in the application and overturn the decision.
We are supporting the local villagers most affected by the proposed industrial 1000-cow unit - the Campaign Against Leighton Farm Expansion (CALFe) - which will be right next door to the village primary school. The Soil Association and Campaign for Real Farming also signed the letter.
Compassion's Director of Public Affairs Joyce D'Silva said: "Dairy farming is at a crossroads. Going down the industrial farming route is likely to ruin the countryside, wreck the livelihoods of existing farmers and cause misery to thousands of cows. We urge farmers and retailers to support pasture-based farming, which benefits both countryside and cows and offers the more ethical product which consumers prefer."
Addressing members of the Welsh Assembly and MPs at an event in Cardiff, WSPA Chief Executive Mike Baker said "It concerns us that just six councillors could in effect make such a decision; the ripples caused by this will go far beyond Welshpool. If developers feel they can build a mega dairy in rural Wales, which has some of the best pasture in Britain, then this is a worrying precedent to set."
The development is also opposed by the Countryside Council for Wales, the historic monuments agency Cadw, the Campaign for the Protection of Rural Wales, the National Trust and Powys Teaching Health Board, who are concerned about the air quality of the farm and its proximity to Leighton primary school. CALFe and CPRW have also written to the Welsh Assembly asking for the planning application to be called in.