Vale of Glamorgan Council says it will review where it sources food produce following concerns over imported chicken in school meals.
Figures published by the Countryside Alliance revealed around two thirds of poultry (68%) served in Vale schools were sourced from China and Thailand.
The county council said it was not always possible to use local ingredients because of the costs involved.
An investigation found that neighbouring Bridgend County Borough Council was one of only two local authorities in Wales which sourced all of its chicken meat for schools was made in the UK.
By contrast, other councils such as Merthyr Tydfil imported as much as 99.3% of poultry in school meals from Thailand and China, while Caerphilly had sourced around 87.3% of meat outside the EU - although the council had switched to sourcing from inside the EU last September.
20 of Wales' 22 local councils responded to FOI (Freedom of Information) requests.
Rachel Evans, the Countryside Alliance's director in Wales, called on the Welsh Government to "take urgent action to ensure that public money spent on school meals supports Welsh farming, high food standards and sustainability."
She added: "I’m shocked and disappointed that, when we have such high quality Welsh and British produce, including chickens farmed with some of the best welfare standards in the world, so much of the chicken our children are eating is being shipped in from the other side of the world."
A spokesperson for Vale of Glamorgan Council told Bro Radio News: "We work closely with our suppliers to provide produce that offers quality and value for money. Wherever possible, we use local ingredients, but this is not always possible due to costs involved."
"The council will meet with its supplier to further discuss the sourcing of products and review current procurement arrangements."
Cllr Rhys Thomas, chair of the council's education committee, said: "It's mind boggling that the Vale Council chooses to ship the bulk of its chicken from China and Thailand instead of sourcing quality chicken from Welsh farms."
"Not only does that undermine hard-working local farmers, it raises serious questions about animal welfare and food quality."
"The Labour-run council should back our farmers and use local produce instead of shipping meat from the other side of the world."
The Welsh Local Government Association (WLGA) told BBC Wales that all chicken - regardless of its source - had to meet stringent UK food safety and hygiene standars.
A WLGA spokesman said: "Councils are working to improve sustainability and support local supply chains where possible, while ensuring school meals remain safe, affordable and consistently available."

Concerns raised over what would be the tallest building in Wales
Cladding works at Cardiff Bay appartments approved
GVS celebrate legacy of CEO upon retirement
Operation in Cardiff and the Vale sees over 30 suspected offenders arrested in one day
Soft Plastic Recycling to expand across the Vale of Glamorgan
A number of changes are coming to Cardiff's International Sports Vilage
Barry RFC Proposes New Walking Route Across Reservoir Fields Following Community Feedback
Community groups receive £10k to support bereavement projects across Wales
Residents band together to oppose green space inclusion in redevelopment plans
Penarth shop named Welsh bookshop of the year
Council Tax rise approved by Vale Councillors
Cardiff Airport recognised by Ysgol y Deri parents’ charity for supporting students and families
The go-ahead has been given to relocate a collection at a major Welsh museum to return a “significant room” to the “public realm of the museum”
Spitfire Flights Mark 90th Anniversary of First Flight
Penarth RNLI crew members join RNLI’s Women in Search and Rescue Training Week
Llantwt Major chosen to take part in one-week Town Boost
Paul Chuckle MBE to visit Penarth on "Thank You Tour" for Marie Curie