The President of the Oireachtas Golf Society has apologised for the event in Galway on Wednesday.
Speaking to the Westmeath Examiner, Donie Cassidy said the dinner, which is now being called ‘golfgate’, was held under guidance approved by the Irish Hotels Federation.
The hotel group say the advice is multiple gatherings can be held in the same venue as long as there is separate entrances and toilets.
Mr Cassidy, who is a former Senator and TD, also said he will co-operate fully with the Garda investigation, and it was not their intention to disregard public health advice.
The EU Commissioner Phil Hogan, who also attended the event, is facing mounting pressure to resign from his role.
Labour Leader Alan Kelly says he knew the rules when attending and that his position is untenable.
Commissioner Hogan confirmed on Friday morning that he had attended the event but at the time offered no apology.
He later apologised following huge pressure from the public and calls from Taoiseach Micheál Martin for him to do so.
Despite the apology, Commissioner Hogan has made no indication that he intends to resign from his role as EU Commissioner.
A Dáil official with responsibility for health and safety was also found to have been in attendance at the event.
Captain of the Guard in Leinster House, John Flaherty, attended the dinner, as reported by the Irish Examiner.
The event, which took place in the Station House Hotel in Clifden was attended by over 80 people, including a number of TDs and Senator, both past and present.
Yesterday, gardaí confirmed they are investigating the alleged breach of Covid-19 restrictions at the event in Connemara.
Under the current restrictions, it is an offence to organise an indoor event for more than 50 people, or an outdoor event for more than 200 people.
Offences are punishable by a fine of up to €2,500, up to six months imprisonment, or a combination of both