Six men and a teenager were arrested by the PSNI near Dungannon following a request from Gardaí investigating a stabbing in Co Longford.
Police said an armed response unit stopped a vehicle travelling on the M1 towards Portadown on Tuesday January 30. A large bladed weapon was found during a search. Six men and the 17-year-old youth were arrested by the PSNI.
The arrests are thought to be in connection with a stabbing of a man in his 40s in the Ballymahon area of Co Longford during the early hours of Tuesday. The altercation involved members of two related families who had travelled to the Republic from Britain for a memorial event in Longford town.
A PSNI spokesman said: “Officers from PSNI, working with colleagues in An Garda Síochána arrested a male aged 17 on suspicion of grievous bodily harm and six men aged 18, 19, 24, 30, 37 and 44 in the Portadown and Belfast areas.
“They were arrested on suspicion of a number of offences including wounding with intent and possession of an offensive weapon.”
All seven remain in custody.