Sectarian chanting by fans during Linfield's Unite the Union Champions Cup tie against Dundalk has been condemned.
In footage from the game, in which the Blues were handily defeated 6-0 at Oriel Park, some Dundalk fans can be heard singing "Ooh Ahh Up The Ra".
There were also reports of sectarian chanting from a small section of Linfield fans.
The game was the second leg of the final of the inaugural Unite the Union Champions Cup, the Football Association of Ireland (FAI) and Irish Football Association's (IFA) attempt to add a cross-border element to football on the island.
It was played amid talk of the formation of an All-Island League, an idea that has been rejected by the Irish Football Association.
During the first leg of the tie at Belfast's Windsor Park last week there were reports of sectarian singing by both home and away fans.
Following the game Dundalk boss Vinny Perth said he was '"very disappointed" at a small section of the travelling support.
Monday night's clash saw much of the same, with fans from both teams taking to Twitter to voice their anger at the behaviour of fellow supporters.
BBC broadcaster Stephen Watson described the behaviour of the Dundalk fans as "dreadful".
"The thought of an All-Island League will never happen in my opinion," he said.
The Irish Football Association condemned the chanting saying it was committed to improving fan behaviour.
After Linfieldâs 6 nil defeat by Dundalk - and the dreadful behaviour of the Dundalk fans singing pro-IRA songs, the thought of an All Island League will never happen in my opinion.. pic.twitter.com/M3e93NlGem— Stephen Watson (@winkerwatson1) November 11, 2019
One supporter tweeted: "I'm a Linfield fan. The ignorant chants of Linfield and Dundalk fans literally turns my stomach.
"If you want to carry on like this, please don’t come to the football.
"You are selfish and ruining it for the rest of us. You are not cool or funny and you were not in the IRA/UVF."
Very disappointing chants from a a small section of Dundalk supporters tonight against Linfield, very audible IRA chants on the TV.— Domestic Ireland (@DomesticIreland) November 11, 2019
A small minority letting not only Dundalk down but the League of Ireland as well...
We need to move with the times and set a good example.
Another wrote: "Very disappointing chants from a a small section of Dundalk supporters tonight against Linfield, very audible IRA chants on the TV.
"A small minority letting not only Dundalk down but the League of Ireland as well...
"We need to move with the times and set a good example."
Linfield visit to Dundalk, a missed opportunity to extend a heartfelt welcome to visitors. Tribal hostility is not confined to NI. I'm sad, having been Chair of Dundalk Town Council as ceasefires began in 94, as peace was coming. Let us keep the resolve to create enduring peace.— Neil Patrick McCann (@Koberah) November 12, 2019
Neil McCann, a former Dundalk councillor, said: "Linfield visit to Dundalk, a missed opportunity to extend a heartfelt welcome to visitors. Tribal hostility is not confined to NI.
"I'm sad, having been Chair of Dundalk Town Council as ceasefires began in 94, as peace was coming. Let us keep the resolve to create enduring peace."
Many supporters also speculated that the behaviour of some fans showed the divisions that could hinder any potential All-Island league.
In a bid to ensure the game went off without incident, a security operation was put in place that made bus travel for Linfield fans mandatory.
Their buses, however, got lost en route to the stadium due to roadworks and fans arrived just a few minutes before kickoff.
When contacted by the Belfast Telegraph, an IFA spokesperson said: "The Irish Football Association condemns sectarianism of any kind.
"The association is continually working with clubs and supporters’ groups to ensure fans behave in an appropriate manner."
The Football Association of Ireland - which is responsible for the game in the Republic - was also contacted for a response.