Another regional brewery boss has called for a review of progressive beer duty (PBD) to create a fair system for all small brewers.
Guy Newell, of the Butcombe Brewery near Bristol, says current duty concessions are "too generous" for companies with the smallest volumes.
Newell told the annual conference of the Society of Independent Brewers (Siba) that the tax allowances had created an "unlevel playing field".
The argument that bigger regional brewers have tied estates and it is all honey and roses for them is fatally flawedGuy Newell, of the Butcombe Brewery.
"Some brewers have suddenly found themselves not competitive and it is destabilising the market," he said.
Some companies can claim duty relief of more than £45 per barrel, which Newell said was simply too much.
"Brewers should come up with a fair system. Some are asking why people coming into the industry are getting what amounts to a state subsidy," he said.
Newell, who founded the Beer Seller company before selling out to Scottish & Newcastle for £32m, conceded his views would not go down well with brewers who had reaped major benefits from a sliding scale of duty.
"The argument that bigger regional brewers have tied estates and it is all honey and roses for them is fatally flawed," Newell claimed.
Bigger companies have claimed some small brewers are using the tax allowances to discount brands and undercut rivals.
They say too few small independents are using money saved to invest in new plant and extra staff.