Ministers were supposed to have made up their minds last month but were facing strong lobbying from some of the retailers, said the NFU horticulture board.
Chairman Sarah Pettitt said: "A decision was originally due at the beginning of November and it's disappointing we have had this delay. The key supermarkets are clearly running around the halls of government citing gloom and doom. There's been a lot of lobbying and I think that has led to the delay."
The Competition Commission made a formal recommendation to the Government to introduce a supermarket ombudsman in August after leading supermarkets failed to sign up to voluntary proposals.
Pettitt estimates the cost of launching and running an ombudsman to be £5m, which she called "minuscule" against a retail market worth £110bn.
Grocery Market Action Group chair Andrew George MP said: "The Government is trying to sit on its hands for as long as possible. The Competition Commission can request a response within 90 days but the department is not required to accede."
The Liberal Democrat member for Cornwall and Scilly Isles added: "I'm very concerned. I'm sure the department is having talks with supermarkets. I've asked who and when and if I'm not told I will make a Freedom of Information request."
George, who last month launched an early-day motion signed by more than 50 MPs in support of an ombudsman, added that Labour MP Albert Owen was prepared to use a private-member's bill to force the issue.
British Independent Fruit Growers Association chair John Breach said he was not surprised about the delay because the group had been calling for an ombudsman for 15 years and had given evidence to a select committee back in 1995.
He condemned the "audacity" of the four biggest supermarkets, which cornered four-fifths of the grocery market, to warn that paying for an ombudsman would push up the cost of food.
NFU chief horticultural adviser Phil Hudson said: "We are still waiting for a decision from the Government even though the case has been made by the commission."
A representative insisted that the Government will respond before the end of the year but said he could not speculate on the decision.
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