The cost of Canada's mission in Afghanistan could be more than double what the Conservative government has estimated, an Ottawa think-tank suggested on Wednesday, a day before the official tally is slated for release.

Prime Minister Stephen Harper's government has previously estimated that the total cost to date of Canada's mission, which began in 2002, is less than $8 billion.

That's less than half the $17.2 billion that the Rideau Institute predicted in a study entitled The Cost of the War and the End of Peacekeeping, which was released Wednesday. The institute's tally includes the cost of ammunition, equipment, military salaries, health care, disability and death benefits and economic aid projects.

The independent research institute, which is a non-profit organization, said Canadians can expect another $11.1 billion to be spent between now and 2011, which is the date the Conservative government has pledged to withdraw most of Canada's military forces from combat duties in Afghanistan.

"It's clear that the government's budgetary and foreign policy hands will be tied if it intends to keep our troops in Afghanistan through December 2011," said Steven Staples, president of the institute.

A report by Parliamentary budget officer Kevin Page, entitled The Fiscal Impact of the Canadian Mission in Afghanistan, will be made public Thursday morning.

While the report has been ready for weeks, its release required the support of all party leaders. They, as well as Harper, gave their blessings last month — despite concerns it could sway how Canadians cast their ballots in the federal election on Oct. 14.

Public opinion surveys have repeatedly shown that Canadians — especially voters in the key electoral battleground of Quebec — are lukewarm to the mission.

The Rideau study also predicted additional costs of up to $7.6 billion, once factors such as health care, disability and death benefits for wounded or killed soldiers are taken into account, bringing the eventual total to more than $28 billion by 2011.

98 Canadians killed

Page has already said his report will consider the costs of veterans programs, while he is also expected to factor in more traditional spending points such as military salaries and equipment purchases.

Canada has about 2,500 troops in Afghanistan's volatile province of Kandahar.

The mission started in early 2002, shortly after the U.S.-led invasion that toppled the Taliban government, although some Canadian soldiers on exchange with the American military were in Afghanistan months earlier.

To date, 98 Canadians, including one diplomat, have lost their lives serving in the conflict.

The institute study's co-author, David Macdonald, said the Defence Department has reduced its United Nations peacekeeping contributions by more than 80 per cent since the Afghan mission began, to $15.6 million in 2008-09 from $94.1 million in 2000-01.

Staples said "the cost of the war in Afghanistan has essentially resulted in the abandonment of Canada's 50-year commitment to UN peacekeeping."

The study also found that about 167 Canadian soldiers and police officers were deployed on peacekeeping missions as of July of this year, ranking Canada 53rd of 119 contributing nations.

With files from the Canadian Press