Minister for Foreign Affairs Simon Coveney has defended asking his secretary general to oversee a review into the 17 June 2020 gathering of officials during Covid-19 restrictions, saying he is the right person to examine the "reputational damage" caused.

In a letter to the Oireachtas Committee on Foreign Affairs, and seen by RTÉ News, Minister Coveney acknowledged the criticism of the gathering, which saw 20 officials photographed together with a bottle of champagne after Ireland's successful United Nations security council seat bid.

However, addressing specific concerns raised by the committee on why the review was being conducted by a department official and not independently, Minister Coveney said his department's new secretary general Joe Hackett "was not at the gathering in June 2020" and is therefore the right person to lead the investigation.

"The current secretary general was not at the gathering in June 2020 and was not involved in the UN Security Council campaign.

"He is the accounting officer for the department and as this matter is a workplace incident that has caused reputational damage to the department, it is correct and appropriate for the secretary general to lead this review," Minister Coveney wrote.

In his correspondence to the committee - which is seeking to question Minister Coveney over the gathering once the department's review is complete and has raised concerns over it being led by the secretary general - the minister also confirmed the review will be completed by 31 January.

In a separate letter to the committee, the Department of Foreign Affairs also confirmed the exact scope and terms of reference of its review into what happened, which includes:

- the workplace arrangements and public health advice in the department on 17 June 2020

- the "circumstances in which staff were present" in the department on that day

- the "nature of the work that required on-site presence"

- why officials gathered together after the vote

- and "all relevant timelines" relating to the incident.

The second letter also confirmed the human resources unit of the Department of Foreign Affairs will question all officials involved in what happened.

It said the "review team" will also request "all documentation or records from across the department that it considers necessary for carrying out the review".

It added that the review will be completed "no later" than 31 January and that the review team intends to publish its findings "in full".

At a private meeting on Tuesday, the cross-party Oireachtas Committee on Foreign Affairs agreed to question Minister Coveney over the issue after the review is completed.

The committee also formally voiced its concerns over the decision to ask the department's secretary general Joe Hackett to lead the review into what happened.