Four more Sydney NRL clubs have joined South Sydney in claiming they are under serious threat of extinction due to the ongoing financial crisis in rugby league.

While the Rabbitohs are reportedly struggling to make ends meet under the co-ownership of Peter Holmes a Court and Hollywood actor Russell Crowe, several other Sydney clubs are feeling the pinch of the NSW government's increased poker machine taxes.

Parramatta, St George Illawarra, Penrith and the Bulldogs - all heavily reliant on grants from leagues clubs - admitted their future was far from certain if the status quo remained.

"We're under massive pressure as well, just like every other club in Sydney," Bulldogs chief executive Todd Greenberg said.

"We're on notice that our grant may well be affected going into next year.

"We're all in the same boat here and the future livelihood of Sydney clubs are all under threat."

The remaining Sydney clubs - Manly, Wests Tigers and the Sydney Roosters - said while they had moved away from being so reliant on leagues club grants, they too had been and would continue to be grossly affected by a reduction in funding.

Cronulla did not return AAP's calls.

Parramatta boss Dennis Fitzgerald, who will be part of a sub-committee which will appeal to the government for a relaxation in tax rules, said he could not guarantee the Eels' long-term future.

"I can't give an iron-clad guarantee," he said.

"We as club managers probably underestimated the effect that the poker machines taxes, effectively it's a 50 per cent increase in what we were planning but with other restrictions such as reduced machines for the big clubs like ourselves, reduced trading hours which makes a hell of a difference and then the smoking bans ... it is a very drastic situation.

"Parramatta Leagues Club ... the fourth biggest (in NSW) as far as machine revenues is concerned, we had a loss of $4 million and we're budgeting for a loss of $3 million this year.

"If the government wants to see a whole host of licensed clubs together with NRL clubs collapse, they won't do anything.

"If they want to help us, they will come to the party and coming to the party means reducing those tax rates."

NRL chief executive David Gallop met with club bosses this week and admitted the outlook was bleak.

"The message is coming through in no uncertain terms that some Sydney NRL clubs will die if things don't change," Gallop said.

South Sydney director of football operations Shane Richardson moved to reassure fans the club was doing everything it could do to secure its long-term future after Holmes a Court said "I can't guarantee Souths will survive".

There have been reports Holmes a Court and Crowe are set to scale back their investment in the club amid talk of a rift between the pair.

"It's business as usual for us," Richardson said.

"Now is a time for the members that have stuck by the South Sydney Rabbitohs to support the club.

"We lead the game in terms of growth in membership and sponsorship, but we need everyone who supports the club to stick with us and encourage other supporters to get on board and support what we're trying to achieve."