Cardiff Blues chief executive Richard Holland has called on the Welsh government to rethink its financial offering amid the coronavirus pandemic.
Holland cited £20m offered in loans and grants to Scottish rugby while English top-flight clubs will benefit from around £44m, largely in loans
"This is now a fight for survival," said Holland in a statement.
The Welsh government has a £14m sport and leisure recovery fund, which does not include repayable loans.
However, Blues and fellow Welsh regions Ospreys, Scarlets and Dragons have taken out loans negotiated by the Welsh Rugby Union totalling £20m.
In his statement, Holland said: "We reiterate our calls for the Welsh government to provide clear guidance and financial support to professional rugby in Wales.
"This is now a fight for survival.
"Following today's announcement that the Scottish Government have provided financial aid to sport in Scotland, including £20m to rugby, Wales is now the only part of the United Kingdom not to benefit from similar support.
"As it stands, rugby in England will also receive £135m, including £59m to the Premiership clubs, and the Irish Rugby Union have already received £16m.
"This equates to £4-5m of Government support to each professional club in Britain and Ireland, with the exception of Wales who have received nothing.
"It is absolutely essential that professional rugby receives similar levels of support from our government.
"Without this support the future for our entire national game, which contributes so much to the economy and general society, is bleak."
Rugby union in Scotland will receive £20m. Of that £5m is in loans and £15m grants.
When the UK government announced a £300m Sports Winter Survival Package for sports in England, it emphasised the final amount received by each sport/organisation may differ from the amounts set out when final decisions are made by an independent decision-making board, and supported by Sport England.
Preliminary figures included £59m for English Premiership clubs from a total of £135m for the sport overall there.
The Welsh government has previously said: "The clubs have been entitled to support from the different stages of the Welsh government economic resilience fund, as well UK government furlough and job retention schemes.
"The Welsh government announced a £14m sport and leisure recovery fund to help the sector deal with the pandemic and to prepare for a safe return of crowds.
"This has been a challenging year for sport and we are working with Sport Wales and the governing bodies to assess what additional support may be required."
Blues and their fellow Welsh regions along were recently among 15 leading Welsh sports organisations to call on the Welsh government to allow fans to return to games.