Opponents ranging from singer Willie Nelson to a bipartisan group of 48 members of Congress had joined organic farmers in attacking the USDA's controversial proposal.

The Agriculture Department was expected to announce Friday that it would in effect eliminate the controversial rules, and start over again, the sources said.

"The USDA is going to say that they have decided to fundamentally revise the organic program rules," said one organic industry official, speaking on condition of anonymity. "They plan to re-propose the organic rules for another round of public comment."

The department was expected to indicate that while it considers irradiation, genetically modified material and sewage sludge to be safe, they are not appropriate for foodslabelled as "organic," the source said.

The outpouring of letters and E-mail from the public -- a record for any USDA policy issue -- had overwhelmingly opposed permitting irradiation, sewage sludge or bioengineered plants to be used in producing organic products.

The department issued the proposed rules last winter to set standards for organic foods after years of pleading by the fast-growing organic industry. Currently, several dozen states and local agencies certify food as organic but use widely varying standards.

Organic foods have blossomed into a profitable niche, generating more than $3.5 billion in US sales. Industry experts attribute the growth largely to aging baby-boomers, who are seeking food, soaps and other items made with fewer chemicals.

But organic farmers protested that the proposed federal rules were intended to favour large agri-businesses interested in the growing industry.

"We are expecting some type of reversal by the USDA. There have simply been too many people too upset bythis," said one congressional aide, who said his office had received some 10,000 letters from angry constituents.

"The USDA proposal was unacceptable -- people are spending a lot of money on organic food and expect to get what they pay for," he added.

Agriculture Secretary Dan Glickman repeatedly said in recent weeks that the proposed organic rules did not endorse the trio of controversial techniques, and could be dramatically changed before being finalised.

Even Monsanto Corp., one of the biggest names in biotechnology, urged the USDA to defer any decision on genetically engineered plants for three years.

The use of genetically modified organisms has been a political hot potato for the USDA. For years, the department has aggressively promoted genetically altered seeds for soybeans and corn to improve quality and yield, and has criticised trading partners who balked at the seeds.

Sewage sludge, collected by municipal sewage plants, is used by some large agribusiness firms as a cheap and convenientfertiliser. Meat companies are showing an increasing interest in irradiation, the use of tiny doses of gamma rays or X-rays, to kill foodborne bacteria.