A high-profile former GAA star has been accused of cyberbullying over a tweet saying an SDLP woman had a face "like the back of a van".
Co Armagh principal Jarlath Burns is now under investigation by school bosses, it can be revealed.
The Council for Catholic Maintained Schools (CCMS) confirmed it was "addressing" remarks on Twitter relating to former MLA Karen McKevitt.
The remarks appeared on the Twitter account of the GAA hero, who denied it was him who posted them.
The former Armagh captain is headmaster at St Paul's High School in Bessbrook.
The tweet, which was quickly taken down, contained a photograph of Mrs McKevitt's van shot from a car overtaking her on the road.
It included the caption: "Look who was in front of me this evening. Face like the back of a van."
Former South Down MLA Mrs McKevitt, who is standing in next month's Assembly election in Newry and Armagh said she could not make any comment after lodging a formal complaint with CCMS.
A statement from the Catholic schools body said: "CCMS can confirm that it received correspondence in relation to a comment posted on a social media account of one of its principals.
"It can give its assurance that the matter is being addressed."
Mr Burns said he had been attending a GAA match when a number of tweets - which did not represent his values or opinions - were issued.
On becoming aware of them he said they were immediately deleted. One of the tweets, he confirmed, referred to a member of the SDLP.
He explained he had contacted the SDLP's Press office, which he said had been satisfied, and accepted his explanation.
He added that despite making a number of requests to meet Mrs McKevitt "at this stage this has not occurred".
A SDLP spokeswoman said the incident was being regarded as a prime example of "cyberbullying".
"Karen is very upset and, of course, humiliated by this," she said.
"She has lodged a formal complaint and does not think it would be appropriate to meet Mr Burns until the outworking of that."
Mr Burns has been in the headlines several times. Recently he said he would support an end to the playing of the Irish national anthem at GAA matches if it helped the sport reach out to Protestants.
Now chairman of the rules committee at GAA headquarters in Croke Park and tipped as a potential future head of the organisation, he first came to public prominence for non-sporting reasons as a member of the Eames-Bradley group that produced a controversial report on dealing with the legacy of the Troubles.
Last July he praised the outreach work of the Orange Order, and defended the organisation after complaints that a tricolour was not flown at the reopening of its Belfast museum despite the fact the Irish Government had provided funding for it.
He also said on TV that the GAA needed to "reach out" to the unionist community.