OTTAWA - The federal agency responsible for maintaining grain quality standards has warned its workers they could face disciplinary action if they publicly criticize controversial amendments to the Grain Act.

The Canadian Grain Commission's director of human resources sent a memo to employees last December outlining what they can, and cannot, say publicly about the government's proposed amendments to the Grain Act.

The Agriculture Union for the Public Service Alliance of Canada released the memo Wednesday.

In it, human resources director Diane Shapiro says commission employees are free to express their views about the amendments to their members of Parliament, so long as they "do not publicly criticize the government of Canada.''

Doing so, Shapiro wrote, would "bring into question your ability to perform your employment duties and carry out government policy and programs in an impartial manner.''

Workers who identify themselves as grain commission workers on web sites and blogs, or in newspapers or at public meetings, and criticize government policy face disciplinary or administrative action, she wrote.

"You could create a perception that your views of government policy are not impartial and that you may not be able to follow or apply government policy in an impartial manner,'' Shapiro wrote.

Bob Kingston, the union's executive director, said grain commission employees take the memo seriously and have repeatedly raised concerns about it at union meetings.

"The fear of losing your job over this is real,'' he said.

Grain commission spokesman Remi Gosselin said the memo was not a gag order from Prime Minister Stephen Harper's Conservative government. He added the agency is simply following long-standing Treasury Board policy.

"This is in no way tied to the Harper government. It's not a gag order. The policy itself predates the Harper government. It's been in place for quite some time,'' Gosselin said.

In the House of Commons on Wednesday, Agriculture Minister Gerry Ritz angrily denied the Conservatives had anything to do with what he called an "internal document.''

"More baseless allegations,'' he said. "There's absolutely nothing to this. This memo had nothing to do with this government.''

Shapiro was out of the office Wednesday and didn't respond to an e-mail seeking comment.

The Agriculture Union says proposed government amendments to eliminate mandatory weighing and inspection will hinder Canada's ability to market high-quality product overseas.

The union says high-quality grain will be mixed with lower-quality product if the government scraps mandatory weighing and inspection.

It says that would eliminate the premium paid for top-quality Canadian grain by international buyers.

But Gosselin said eliminating mandatory weighing and inspection would not impact grain quality.

"In the past, about 30 or 40 years ago, you had a lot more players in western Canada handling grain and there was a higher risk of co-mingling between different classes of grain,'' he said.

"But now, because there have been significant consolidations within the grain industry, and there's only a few players ... that service is no longer required.''

In a release last December, Ritz said the government is "making sure the CGC continues to meet the needs of farmers and the entire industry.''

But Kingston has said the changes -- proposed by the Conservatives last December -- are based on ideology and not what's in the best interests of farmers.

The memo surfaced at a time when some have criticized the federal government for sending a chill through the public service by cracking down on dissidents.

Auditor General Sheila Fraser has said the government's decision last month to fire Linda Keen as head of the Canadian Nuclear Safety Commission raised concerns about the independence of regulatory bodies.

Natural Resources Minister Gary Lunn fired Keen after she refused to authorize restarting the aging Chalk River reactor, which triggered a critical shortage of medical isotopes.