Scottish Rugby face losses of £30m if supporters are not allowed to return to stadiums soon, says Mark Dodson.
Plans for a phased return of fans to sporting events in Scotland have been paused amid rising coronavirus cases.
"Our current estimate of the impact on Scottish Rugby caused by Covid-19 is £18m," chief executive Dodson said.
"If the restrictions continue until the end of the season the impact increases to £30m. The need for government help is clear."
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A small number of fans were allowed to attend Edinburgh's last match of the regular Pro14 season against Glasgow Warriors at Murrayfield and two test events with supporters have been held in football's Scottish Premiership.
However, plans to have fans at a further Premiership match last weekend were shelved and the 5 October date set for gradually reintroducing crowds at events was this week delayed. Edinburgh and Glasgow will return to Pro14 action behind closed doors early next month.
Scotland are scheduled to host France and Fiji at Murrayfield in November and hopes are fading fast that any supporters will be inside the stadium, with concern also growing over the viability of having fans at Scotland's three home Six Nations matches in the spring.
"We will require a different set of measures to deal with the situation," explained Dodson.
The chief executive's comments follow cautionary words from his counterpart at World Rugby, Brett Gosper, who said: "It's estimated that the home unions could lose more than £100m if closed doors rugby continues. If things don't start getting better by springtime we are going to be in a more drastic situation."
Word Rugby has advanced some financial support to troubled unions but their funding is expected to run out early next year.
The RFU at Twickenham has warned of "severe consequences for the sport" if venues remain closed, with chief executive Bill Sweeney citing a £122m reduction in revenue and a £46m loss if fans do not return in time for the autumn Tests. If there are still no supporters during the Six Nations, Sweeney estimates a £138m reduction in revenue and a loss of £60m.
His counterpart in Wales, Gareth Davies, is seeking a £20m loan to help Welsh rugby while in Ireland, chief executive Philip Browne has warned "rugby infrastructure built over 150 years is under threat".
Browne added that Ireland's net losses in 2020 will be "catastrophic". He said that if the worst projections are realised next year "the very nature of professional rugby on the island would be under significant threat in 2021".