British PSNI police and Army patrols crossed over the Border into the 26 Counties on Wednesday night, sparking local anger in north County Louth.
Around 20 troops were in the Omeath area on Wednesday night, while two PSNI officers were also spotted driving an unmarked car through the village.
When the matter was raised by the Dublin government through the Anglo-Irish Secretariat in Belfast, British officials denied that there were any incursions.
A spokesperson for the PSNI admitted joint police and British Army patrols were operating in the Border area near Omeath on that night. The patrols were said by local people to have spent over an hour in County Louth, and were seen congregating around a derelict house and passing through people's gardens in the village.
The Department of Foreign Affairs requested a report from local gardai, who had taken statements from residents in the area. These showed that there was a complete conflict between the residents' version of events and that of the British authorities.
Louth Sinn Féin TD, Arthur Morgan demanded an apology from the British authorities, saying local people were fed up with excuses about map-reading errors.
One angry Omeath man claimed he actually discovered three soldiers in his back garden but was afraid to challenge them because they were obviously armed.
Peter McGuigan said they appeared to have jumped over a wall into the rear of the property, and he asked them what they were doing and they left.
However, he could see they were armed and said he did not challenge them too forcefully. ``There is no excuse for this and they can't claim they were lost.''