OTTAWA - Labour Minister Jean-Pierre Blackburn spent almost $150,000 on rental aircraft flying around Quebec last year but didn't declare any of the flights as a travel expense, documents show.

In fact, the majority of the flights on privately hired planes don't show up anywhere in Blackburn's public disclosure of ministerial travel and were only revealed through an Access to Information request by NDP researchers.

NDP MP Pat Martin says it's all part of a "disturbing lack of transparency'' in the minority Conservative government.

"We don't mind ministers spending. It's normal,'' said Martin. "We want to know how much and how.''

Blackburn also serves as Prime Minister Stephen Harper's minister for economic development in Quebec, and it was apparently in this role that he used the charters. But only eight of about 25 contracted flights are listed in his quarterly "proactive disclosure" of expenses for 2006, which cover both labour and economic development duties.

In each of those eight trips, the Conservative minister listed air fare costs as zero.

In fact, those flights cost Canadian taxpayers more than $93,000 in aircraft rental.

At least another 14 trips totaling more than $56,000 by rented aircraft on which Blackburn is listed as a passenger are nowhere to be found in the minister's public travel disclosures. There were also 10 flights involving four different backbench Quebec Conservative MPs that cost another $30,000.

Blackburn did publicly post $11,138 worth of flights on commercial airlines in 2006, but nothing for rentals.

The totals were only revealed by cross-referencing the government's aircraft rental logs, which show passenger manifests, dates, destinations and costs -- obtained under the Access to Information law --  against the "proactive disclosures'' of ministers on their web sites.

Blackburn's office denies he is trying to hide anything.

"A big part of the minister's expenses are related to his work for the department, so they pay for it and disclose it,'' said Michel Lalonde, Blackburn's chief of staff.

"The minister's disclosure is for what he spends himself, in his functions as a minister.''

For instance, during one trip last August to the Saguenay region aboard a rented aircraft, Blackburn's press secretary Roxane Marchand spent almost $2,000 on "other transportation'' and meals -- not including air fare -- while her boss showed a total of $115.

Access documents, meanwhile, show the department was billed $2,279 for the charter for that trip.

"It's disclosed somewhere, it's public,'' said Lalonde. "And ultimately, we all know it's linked to the minister's duties anyway. He's always the one who has to answer questions.''

While Blackburn's officials vehemently argue his expenses are all disclosed, there appears to be some confusion over when his ministerial duties should somehow be counted as departmental expenses.

The revelations come as Tory House leader Peter Van Loan launches what he's calling "Democratic Reform Week'' in the Commons, a week designed to highlight the minority government's accountability measures.

But many of  the new rules appear aimed at Conservative adversaries as much as at general good governance.

An official from the Prime Minister's Office recently followed a journalist off Parliament Hill, then approached the reporter to challenge a story about the PMO's refusal to disclose how Harper's travelling hairdresser is being paid.

The official told the reporter three times that accountability measures are for crooks, not honest people.

It appears to be a theme in the Harper government.

While stressing the need for clear rules and transparency for others, the cabinet continues to tightly control information, censor documents and only selectively disclose ministerial expenses.

Martin of the NDP has been one of the government's strongest opposition supporters in pushing through its vaunted Accountability Act. He says now he spent a lot of "political capital'' backing the Tories and has become seriously disillusioned.

"There is a scheme going on to mislead Canadians about how the Conservatives are spending money,'' said the Winnipeg MP. "It's contradictory because they have cried bloody murder for years that the Liberals were not transparent and accountable, and now they are doing the same.''

  "There is a deliberate conspiracy to masquerade the costs.''

Van Loan says the government remains committed to its accountability agenda and denies there is any lack of transparency on expenses.

"I think overall there's been pretty good disclosure,'' said the Tory minister. "But there hasn't been a lot for most of us to disclose, because we don't do much in terms of spending and entertaining and travel and all that stuff.''

But outside experts and political opponents have questioned how senior ministers or their political staff can regularly dine out with stakeholders while showing no hospitality expenses. One explanation is that government officials who fall under the "proactive disclosure'' policy are getting others to pick up the tab.

One senior government communications director recently invited a private sector employee to an expensive restaurant in Ottawa, arrived first and ordered an expensive bottle of wine, and at the end of the meal, pushed the bill across the table, flatly stating the guest had to pay.

It is anecdotes like these that make "horsefeathers'' of the Conservative explanation that all expenses are somewhere on the books, says the NDP's Martin.

"We want the whole story,'' said Martin. "If a minister is spending money, we want to know.

"We are detecting a disturbing pattern of lack of transparency among cabinet ministers. We were already sick of this game with the Liberals.''