Shoppers have been unwittingly buying meat from animals that were not stunned when killed under religious rules because it is going unlabelled in supermarkets, a consumer watchdog has warned.

Up to 90,500 animals that were slaughtered as kosher – mostly chickens – could have ended up on store shelves with no wording to tell consumers how the meat was produced, the Food Standards Agency said in a report.

The meat had been rejected as “unfit for religious consumption”, it said.

The revelation prompted both vets’ leaders and the RSPCA to renew calls for a national ban on no-stun slaughter.

Some animals due for religious consumption are stunned, but the figures revealed last year more than 94 million animals were slaughtered without the practice taking place – an average of three animals per second.