Cargill, a major supplier of halal meat in the UK and overseas, conducted a recovery trial in Spain on 8 January 2014, led by the Halal Food Authority (HFA) and carried out by two academics from the University of Bristol.
However a spokesperson for the UK association said it felt the trial was "unethical" due to the way it was done behind closed doors, demonstrating "a lack of respect for the Muslim consumer".
He added that the trial involved "two halal certification companies, already subject to concern by the Muslim community over their certification not meeting the halal criteria, and one poultry company Cargill that churns out high volumes of poultry through the machine slaughter method".
Cargill Meats Europe responded to the claims, stating that its European poultry business supplied certified halal chicken from its UK facility in Newent, near Gloucester.
A spokesperson said: "An electrical stunning process is used, which stuns the birds to minimise stress but does not kill them.
"The birds are then manually killed with a single knife cut by a trained Muslim slaughterman, who speak prayers constantly during the process. Our Newent slaughter process is independently endorsed and approved by the Institute of Islamic Jurisprudence, which inspects our halal process and certifies our products.
"Bristol University undertook an independent study to determine the effect of electrical current and frequency combinations permitted by European regulations during poultry slaughter for the halal market, which Cargill supported as the findings would be pertinent to our business."
To view the results of the study, click here: https://peerj.com/preprints/255/
A motion stating that machine-killed poultry is haram (forbidden) and unacceptable to UK Muslims was signed last month, by the Halal Authority Board.