Five men have been arrested as part of a cross-border investigation into a contamination scare in the Irish pork industry which cost pig producers an estimated £100 million.
Four of the men were detained in Co Tyrone and Co Armagh by detectives belonging to the Police Service of Northern Ireland (PSNI). A fifth man was also arrested in the Irish Republic in connection with the investigation.
At the time of the alert, just before Christmas 2008, shelves across Europe had to be cleared of pork produced in the Irish Republic after traces of dioxins were found in oil used in the making of feed to pigs and cattle.
The four men arrested in Northern Ireland are being questioned on suspicion of fraud by false representation - moving oil without proper authorisation. They are being questioned in Antrim by officers belonging to the PSNI's crime operations department.
The oil was allegedly supplied to producers in the Republic, who lost an estimated £100 million.
Three of the four men arrested in Northern Ireland are from the Dungannon and Coalisland areas of east Tyrone. The fourth was detained in Blackwatertown, Co Armagh. They are aged 43, 29, 27 and 25 and it is understood some of them are related.
Officers in the Republic said a man in his 50s was arrested in Co Monaghan in connection with the investigation. He is being held under Section 4 of the Republic's Criminal Justice Act.
Members of the Garda National Bureau of Criminal Investigation in Dublin, which launched the initial investigation, are liaising with police colleagues north of the border.
An Irish High Court judge ordered a Northern Ireland company to pay £32.2 million damages to a Co Wexford company arising from the animal feed contamination. Mr Justice Peter Kelly ruled that Millstream Recycling Ltd was entitled to the damages against O'Neill Fuels Ltd, of Coalisland, Co Tyrone, which had denied supplying any fuel containing dioxins.
The 2008 recall of Irish pork was ordered after pig meat on a number of farms was found to have had between 80 and 200 times more dioxins than the recognised safety limit. Dioxins such as polychlorinated biphenyls (PCBs) were detected in the biscuit feed meal for pigs and cattle.