THE head of the wine industry's peak body has been forced to apologise for accusing supermarkets of rorting the wine tax rebate system.

Winemakers' Federation of Australia chief executive Stephen Strachan last month described retail chains Coles and Woolworths as "predators".

Mr Strachan said, at the time, the retailers were undermining wineries by exploiting loopholes in the Wine Equalisaton Tax rebate system to obtain below-cost wine for their house brands.

"Retailers are predators and will do everything they possibly can to undermine Australian wine producers' brands," he said. "Their behaviour is absolutely deplorable."

However, in an abrupt backdown that The Weekly Times understands is the result of concerted pressure from at least one of the chains, Mr Strachan this week apologised for his comments.

"The comments made by me ... attributed problems associated with the WET rebate to direct and deliberate initiatives by retailers," Mr Strachan said. "I have no evidence of such action and apologise to any retailers that were affected."

But Winegrape Growers Australia executive director Mark McKenzie refused to back down on his criticism of the retailers.

"The WET rebate was not set up to benefit retailers; it was set up to benefit small and medium wine producers," Mr McKenzie said. "The retailers are putting massive pressure on winery margins and the consequence of that is ... sharply reduced wine grape prices."

A spokeswoman for Woolworths said it was "disappointing a supplier group chose to make unsubstantiated accusations in the first place". "But we ... appreciate the apology and clarification."

Coles was unavailable for comment.