Samples taken from pigs at an abattoir in Northern Ireland are being tested for foot-and-mouth disease.
There are more than 650,000 pigs in Northern Ireland
The chief veterinary officer revealed foot lesions were detected on Monday at the facililty in County Antrim.
They have now been sent for testing to the Institute of Animal Health with initial results expected on Tuesday.
More than 50,000 animals were culled in the 2001 outbreak, most of them sheep and £7.5m was paid to Northern Ireland farmers in compensation.
Chief Veterinary Officer Bert Houston said movement restrictions and other measures had been imposed both at the abattoir and the site where the pigs had originated.
In a statement, he said: "As part of routine surveillance at an abattoir in County Antrim, foot lesions were detected in a number of pigs presented for slaughter.
"As a precautionary measure samples have been taken and are being sent to the Institute for Animal Health in England for testing for foot-and-mouth disease and swine vesicular disease."
Foot-and-mouth arrived in Northern Ireland in 2001 through sheep with four outbreak sites eventually identified.
Across the UK, the 2001 outbreak led to the slaughter of 6.5m animals and is thought to have cost the UK economy £8bn.