The Canadian Wheat Board has filed a lawsuit against the federal government over legislation that aims to open up marketing of western Canadian wheat and barley.

"Prairie farmers are angry that their voices are being ignored," wheat board chairman Allen Oberg said Wednesday announcing the lawsuit at a farm near Winnipeg.

"Today we are launching a legal action in defence of farmers' democratic rights. This right is being stripped away," Oberg said. "We have no choice but to take this stand on behalf of farmers. We will not be intimidated by bullying tactics."

Oberg said the lawsuit, filed in the Federal Court of Canada, argues Ottawa was legally obliged to consult western Canadian farmers prior to introducing Bill C-18.

Agriculture Minister Gerry Ritz has argued that western Canadian farmers shouldn't be forced to sell their grain through the wheat board.

NDP and Liberal MPs say the wheat board is important for keeping prices fair for farmers, and fear large agribusinesses will have an upper hand in dealing with farmers if the wheat board loses its monopoly.

The federal bill that would make sales of wheat and barley through the wheat board voluntary is now before the House of Commons agriculture committee for review. Because Conservative MPs hold the majority on that committee, no significant delays are expected before the legislation is sent back to the House for a final vote.

At least one CWB board member disagreed with the decision to sue the government. Henry Vos of Fairview, Alta., said he couldn't continue serving on the board as a result of the decision to proceed with litigation.

"I believe the Government of Canada's efforts to change the CWB are in the best interests of western Canadian grain producers and I will support their efforts and the efforts of other organizations and individuals committed to bring about positive change for western Canadian farmers," said Vos.

Two of the 10 farmer-elected members of the CWB were in favour of dismantling the single desk selling of wheat and barley, including Vos.

Ritz hopes the wheat board legislation can clear the Senate and become law before the end of 2011, allowing farmers and other businesses involved in the Prairie grain industry to prepare for selling the 2012 wheat and barley crops on the open market.

On Monday, NDP MP Pat Martin asked the ethics commissioner to review potential conflicts of interest on the part of seven Conservative MPs who have personal or family business interests in Prairie grain farming.

Almost 40,000 grain producers took part in a plebiscite run by the wheat board last summer and 62 per cent voted to maintain the monopoly for wheat.