The Republic's last World Cup finals appearance was in 2002
James McClean has said some criticism of the Republic of Ireland's display in the World Cup play-off 5-1 rout by Denmark is "bang out of order".
The Republic winger said on Instagram that the hurt of the defeat would last a "long, long time".
"To stick the boot in and kick players and staff when they are down with some over the top, beyond football comments is bang out of order," said McClean.
The West Brom man did not make clear who he was directing his comments at.
Former Republic midfielder Keith Andrews, who was working as a Sky Sports pundit, described the team's display as they lost an early 1-0 lead as "clueless" while RTE analyst Eamon Dunphy labelled the defeat a "humiliation".
Match report: Republic or Ireland 1-5 DenmarkO'Neill to discuss Republic futureWhich teams have qualified for the World Cup?What you need to know about the World Cup Martin O'Neill was angered by questioning of his tactics in a post-match interviewO'Neill cuts short RTE post-match interview
Republic manager Martin O'Neill cut short a post-match interview with RTE's Tony O'Donoghue after being frustrated with questions over his tactics and the team's latest failure to hold on to an early lead.
McClean admitted that "everyone is entitled to voice their opinion because it [the display] was simply not good enough from us on the night".
However, he made clear his unhappiness at some of the post-match criticism of the players and management.
"Players and staff have been great servants to this country, players and staff that have qualified for a major tournament [Euro 2016] and were unlucky to be knocked out to a great team [France] in the last 16.
"Players and staff that were one game from making it to a World Cup. Players are staff that would anything for this great country.
"I am proud and honoured to be an Irishman and to call everyone of these men fellow country men and team-mates.
"This will hurt deep [but] we have been written off so many times before and just like before we will bounce back."
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Andrews dubbed O'Neill's decision to withdraw central midfielders David Meyler and Harry Arter at half-time, when he introduced Aiden McGeady and Wes Hoolahan, as "gung-ho football", adding that the second half was "pure torture" as the Danes extended their 2-1 interval advantage.
"To witness what we witnessed here tonight... it beggars belief. Clueless. Absolutely clueless," said Andrews.
Denmark manager Age Hareide admitted that he was stunned by the amount of space that Christian Eriksen had been afforded as the Tottenham star helped himself to a brilliant hat-trick.
"Although they shut Eriksen out in Copenhagen, I couldn't believe the amount of space they gave him to exploit here in Dublin," said Hareide, a former team-mate of O'Neill both at Norwich City and Manchester City.
Despite the Republic's failure to reach Russia, O'Neill verbally agreed a contract extension with the Football Association of Ireland last month.
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Source: bbc.com