A 10-year-old girl suffered a severe allergic reaction following an attack at an event hosted by No campaigners in Co Meath.

Muireann DeClár, who is severely allergic to eggs, was sitting on the side of an advertising truck bearing a NO campaign ad when the event was attacked by youths throwing missiles, including eggs.

Muireann suffered a severe allergic reaction, and her life was only saved by the swift reactions of her mother, Aoife, who administered adrenalin at the scene.

The incident took place outside Navan shopping centre at approximately 4.30pm, where No campaigners lead by Paddy Manning were canvassing passers-by.

Disgraceful of No campaign to use the attack on girl in Navan as political tool to blame Yes side. Blame the little thugs that threw egg! — Séamus Kearney (@SeamusjKearney) May 13, 2015

Responding to the incident, Mr. Manning said that Muireann's condition is now believed to be stable although she is still traumatised by the incident, as are her two young brothers and their mother who is six months pregnant.

“In all my years of political activism, I have never witnessed such an act of mindlessness, or a scene so distressing. While the attackers had no way of knowing that Muireann had an allergy, they had every way of knowing that she was a child of about 10 years old," said Mr. Manning.

"The toxic atmosphere created by the Yes campaign is squarely to blame for this incident, of that, there can be no doubt.

"The event in question was a meet and greet, where No campaigners were trying to engage voters in friendly discussion and polite debate about the decision facing the country in a week.

"That the response to that engagement from some who disagree with us was to almost put a child in hospital is absolutely beyond the pale," said Manning.

Marriage ref debate getting v nasty. Mothers and Fathers Matter have just claimed 10 year old hospitalised after attack by “Yes” supporters' — Mick McCaffrey (@mccaffreymick) May 13, 2015

"I call, immediately and in the strongest terms, for an absolute condemnation and distancing of themselves from this incident by the leaders of the Yes campaign, including those at the top of the political parties.

"I would like to extend my sympathies, and the sympathies of everybody in the No campaign to Muireann and her family. They have become the unfortunate victims of a campaign that has lost any and all sense of perspective,” said Mr. Manning.

Gardaí in Navan are currently investigating the incident.