Britain’s biggest farming body has warned that the rise in religious slaughter risks jeopardising Britain’s reputation for high animal welfare standards.

The National Farmers’ Union (NFU) urged the government to crackdown on abattoirs that kill animals before they have been stunned.

More than three million lambs had their throats slit last year while they were still conscious and able to feel pain, double the number in 2011. It is illegal under EU law for abattoirs to kill an animal that has not been stunned, but there are exemptions on religious grounds for halal and kosher food.

Charles Sercombe, head of the NFU’s livestock board, said that farmers were frustrated at the government’s reluctance to confront religious groups within Muslim and Jewish communities over possible alternatives…