Around a quarter of large pig and poultry farms may have failed to register for mandatory new pollution control accreditation.

The NFU said only 930 applications for IPPC accreditation had been received, although 1,200 pig and poultry farmers had been expected to apply. The deadline for registration with the Environment Agency, which costs £333, was 2 March.

Stewart Houston, head of the National Pig Association said: "If anyone hasn't applied for a permit, they must make sure they are correct not to, as the agency knows where they are."