The Merrion Hotel insists a recent outdoor function - hosted by Katherine Zappone at the venue - adhered to public health measures.
50 people attended the outdoor event in Dublin.
Among those in attendance was Tanaiste Leo Varadkar.
The Irish Independent says the function was held six days before Zappone was appointed as special UN envoy for Freedom of Opinion and Expression.
Fine Gael TD Colm Burke says Zappone's position would be "at risk" if it is found the event breached COVID-19 guidelines.
The Merrion Hotel says outdoor events of up to 200 people are allowed, including social events.
However, the Fáilte Ireland guidelines for the return of hospitality say organised events are currently not allowed to take place.
Sinn Féin TD Matt McCarthy says the optics of the dinner do not look good "I do not see how the circumstances or the rationale or the excuses provided change in much ways from what happened in the Clifton Hotel 12 months ago.
"Essentially there was an attempt to beat the regulations by people who put in place the regulations in the first instance."
