Campaigners have raised concerns over the welfare of animals sent for slaughter amid a shortage of carbon dioxide.
Animal Aid said it was worried that animals such as chickens and pigs would suffer undue distress at abattoirs if factories run out of CO₂, which is used to stun them before they are killed.
Alternative methods include electrical stunning which lobbyists say is more cruel than the use of gas.
A CO₂ shortage across northern Europe has prompted warnings over supplies and has forced manufacturers of fizzy drinks and beer to reduce production.
It was reported earlier that animals were being moved from production lines in Scotland to sites in England due to the shortage.
Animal Aid told HuffPost UK: “We are concerned to hear of slaughterhouses running out of the CO₂ they use to stun animals prior to slaughter due to the additional suffering this could entail.
“We have concerns that things may ‘back up’ and there may be overcrowding at point of lairage or back to farms.
“We also have concerns that animals may be subjected to lengthy additional journeys for pigs, from Scotland down to England for example.”
The organisation added that it believes CO₂ is “far from ‘humane’” and causes numerous issues including “breathlessness as well as… immense burning pain”.
PETA UK said it was “concerned because animals suffer regardless of the methods used to kill them – CO₂ or no CO₂.
“The only genuinely compassionate choice is to leave them off our plates, and PETA is here to help anyone who is waking up to the horror of killing animals for food make the transition to cruelty-free living,” the charity, famed for its controversial campaigns, added.
Last week, the British Poultry Council said the shortage was becoming so acute at some factories there were fears supplies of fresh chicken would be hit.
But responding to questions on the issue last night, food chain KFC said it did not expect to be affected.
A spokesperson for the chain told HuffPost: “We’re aware of the industry issue, but this hasn’t yet affected our supplies.”
However, Peri-Peri favourite Nando’s would not confirm if it had adequate supplies of fresh chicken for the weekend.
Another chain, Chicken Cottage, did not respond to a request for comment.
Enquiries to major manufacturers provided a similarly mixed picture.
2 Sisters Food Group, one of KFC’s major suppliers, said it was able to maintain CO₂ levels as normal “thanks to strong contingency planning and innovative procurement provision.”
Another KFC supplier, Moy Park, said it was “aware of issues across Europe”.
“We will continue to monitor this carefully. We are taking appropriate measures to mitigate any impact,” a spokesperson added.