IRFU chief Philip Browne has said the "very existence of professional rugby" in Ireland is under threat unless fans can return in large numbers.

He said the situation would continue to deteriorate "at an alarming rate" if fans were not permitted to return.

"The rugby infrastructure built over 150 years is under threat," he said.

"Irish rugby's net losses in 2020 are catastrophic and are forecast to be in excess of 30m euros.

"It is anticipated that the IRFU and the provinces will continue to burn at least 5m euros a month, primarily on professional wages and costs.

"This is not a sustainable position."

Browne made the comments in front of the Oireachtas (Irish parliamentary) Covid-19 response committee.

He added that the IRFU's cash surplus of 28m euros in June this year was likely to turn into a debt in the region of 10m euros by next summer.

"If these projections were to materialise, the very existence of professional rugby on the island would be under significant threat in 2021," added the IRFU chief executive.

Browne warned that despite cost-cutting measures across the union, including salary cuts of up to 20% and redundancies, the IRFU's current financial position would require "significant additional actions" at the end of 2020 if there is no sight of supporters returning.

He added that the IRFU was likely to be forced to start borrowing in January.

"Pre-Covid, our financial situation was looking quite positive - now we are facing an unprecedented cash flow crisis," he said.

"The absence of a clear pathway to the return of spectators in meaningful numbers means that our perilous financial situation will continue to deteriorate at an alarming rate in to 2021, moving to an unsustainable position by the third quarter of that year if we do not take certain actions."

Ireland's 2020 Six Nations campaign was suspended with two games left to play.

Those game will be completed in October with an autumn international series but the disruption to the Six Nations Championship is still expected to cost the Irish governing body up to 15m euros.

GAA and Football Association of Ireland representatives also spoke in front of the Oireachtas committee on Friday morning and painted similarly bleak pictures about the impact of Covid-19 on their sports.