(Reuters) - Supporters of the Canadian Wheat Board took their protest to Parliament Hill in Ottawa on Tuesday, in a last-ditch effort to sway legislators to keep the world's last major agricultural monopoly.

Several Wheat Board directors, as well as a few Prairie grain farmers, urged the Conservative government to drop plans to end the CWB's marketing monopoly on Western Canadian wheat and barley destined for milling or export.

Legislation to end the monopoly as of August 2012 would allow western farmers to sell grain directly to grain handlers, and may be only a few weeks from becoming law.

Eliminating the Canadian Wheat Board will cost Prairie farmers money, cost Canadian jobs, be a drain on taxpayers and change the nature of the country because thousands of family farms will disappear, CWB Chairman Allen Oberg said in Ottawa.

A Wheat Board spokeswoman said the directors planned to meet with members of Parliament and senators this week in Ottawa.

The CWB monopoly, which has been in place since World War 2, has long divided western farmers. Supporters say the monopoly's marketing clout offers them the greatest returns, but others say they want the same flexibility in selling wheat and barley that they have with crops like canola and oats.

Alberta farmer Brian Otto, a longtime foe of the monopoly and head of the Western Barley Growers Association, said the Wheat Board debate has gone on for decades and farmers have had their say.

The end of the monopoly does not threaten small farms who rely on the CWB to sell their crops, Otto said. 

It's an insult to any farmer in my opinion to tell farmers they don't know how to run their business. Small farmer or large farmer, we're all capable of marketing our own crops.

Canada is the world's top exporter of spring wheat, durum and malting barley.

Sixty-two percent of farmers voted to keep the wheat-marketing monopoly in a non-binding summer plebiscite conducted by the Wheat Board.

Agriculture Minister Gerry Ritz, himself a former farmer from Saskatchewan, has said that vote was flawed.

An open grain market will bring new investment by processors in Western Canada, Ritz said in a statement, noting earlier announcements such as a plan by Alliance Grain Traders for a new durum plant.

The government bill to end the monopoly is expected to pass third and final reading in the House of Commons next week. After that, it needs approval by the Senate and royal assent to become law.

The Conservatives hold a majority of seats in both the House and the Senate, ensuring the legislation will pass.

Once the bill becomes law, likely next month, grain handlers such as Viterra Inc, Richardson International Ltd and Cargill Inc will be allowed to immediately sign forward contracts with farmers for their 2012 grain harvests.

The Wheat Board itself would come under government control and become a smaller grain marketing option for farmers. 

It's unlikely to survive without its monopoly since it has no capital base or ownership of grain-handling facilities, said Ralph Goodale, a Liberal legislator from Saskatchewan.

The CWB and its supporters are also fighting the government through the courts, with a Winnipeg judge hearing the case on December 6.

The CWB maintains the government broke the law by not consulting its board of directors and not holding a farmer vote before introducing legislation to scrap the monopoly.

(Reporting by Rod Nickel in Winnipeg, Manitoba; Editing by Jeffrey Hodgson)