Dundalk FC have cancelled training for Tuesday and ordered Covid-19 tests for the players following a team outing to Belfast on Saturday.
Pictures showing several of the Lilywhites squad emerged on Sunday night, with the players subsequently sent home from training on Monday.
While the club have not commented on the matter as yet, sources close to the Oriel Park outfit suggest that all bar four of the squad made the trip to Belfast for what was a team-bonding experience.
However, the FAI have asked the Co Louth club to explain the circumstances of the trip as it breached inter-county travel regulations, which have subsequently been eased.
While bars and restaurants in Northern Ireland re-opened for outdoor service on April 30, people were urged not to travel cross-border for non-essential purposes.
It remains to be seen whether there will be any implications for the squad ahead of their next game away to Finn Harps in Ballybofey on Friday evening.
This is the latest in a series of blows for Dundalk, who are currently without a manager following the departures of Shane Keegan and Filippo Giovagnoli from the club last month.
Interim boss and club sporting director Jim Magilton was not believed to have been on the outing and is said to have been livid when he learned about it.
The FAI Cup holders have won just two of their opening 10 games in the SSE Airtricity League and this incident will do little to lift morale after a fourth defeat of the campaign at home to Sligo Rovers last Friday.
Fan unrest had already been growing prior to the Belfast incident with a protest against the way the club is being run planned for the next home match against Shamrock Rovers on Friday, May 21.