EU Trade Commissioner Phil Hogan has said he has "complied fully" with the Government's quarantine requirements and has been in Ireland since late July.
There had been calls for Mr Hogan and others to explain why they attended a golf society event in Co Galway this week.
In a statement this evening, Mr Hogan apologised for the "distress caused by his participation".
Among those who had called for an explanation was Taoiseach Micheál Martin, who said he believed Mr Hogan should apologise for his attendance at the event.
Speaking on RTÉ's Six One News, Mr Martin said the commissioner should be far more fulsome in his response and should understand the anger felt by people across the country.
Earlier, a spokesperson for Mr Hogan said he did not break any local lockdown rules since his return to Ireland.
The spokesperson said Mr Hogan arrived in Ireland at the end of July and went to Co Kildare.
They said Mr Hogan left the county on 5 August, before the local restrictions were applied, for a hospital appointment.
In the course of that appointment, the Commissioner tested negative for Covid-19.
The spokesperson added that at the conclusion of that appointment, Mr Hogan went to Co Kilkenny for a period of convalescence and this is where he completed his period of quarantine.
The statement said he travelled to the golf event in Co Galway directly from Co Kilkenny.
The Irish Examiner reported last night that 81 people were at the dinner in Clifden, with guests split into two separate rooms.
This afternoon, an EU Commission spokesperson said Mr Hogan had acted in "good faith" when he attended the event and had received assurances that the event would be held in full compliance with the regulations introduced by the Irish Government.
"Of course with hindsight he regrets the fact that this seems not to be the case. And with hindsight he would not attend an event which is not in line with the obligations," she said.
However, the spokesperson said it was not for the commission to comment further on the number of people who attended this event or on whether the event was or was not compliant with the guidelines and regulations introduced by the Irish Government.
She would not comment on whether Commission President Ursula Von der Leyen had discussed the issue with Mr Hogan, but said they are in regular contact.
A spokesperson for Mr Hogan also said that the commissioner "did not breach any lockdown rules in respect of Co Kildare in attending the golf event in Galway".