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."
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