OTTAWA -- The Harper government has made dramatic cuts in spending on aviation, marine and rail transport safety over the past five years, even as it was touting new safety measures in the transportation sector.

The latest figures from the federal government's public accounts show actual spending by Transport Canada on marine safety has plunged 27 per cent since 2009-10, while aviation and rail safety spending are both down 20 per cent or more.

Budget cuts to marine and rail safety have come over a particularly sensitive period, during which oil-by-rail shipments increased exponentially and the government spent millions promoting the safe transport of oil by tankers on Canada's coasts in order to bolster pipeline approvals.

Last month, Transport Minister Lisa Raitt announced that 10 additional rail safety auditors would be hired across Canada in response to last year's horrific oil train crash in Lac Megantic, Que., which claimed 47 lives.

Raitt says Transport Canada has plenty of budget room to handle the new hires without additional funding.

"While there have been spending cuts, rail safety oversight activities have not been cut," Ashley Kelahear, Raitt's spokeswoman, said in an email Monday.

"The safety and security of Canadians remain our government's top priorities."

An official with Transport Canada said in an email that "core services remain properly funded and aligned with departmental priorities."

"Savings were deliberately focused on reduction of overhead, consolidation of administrative and support services."

That's precisely the claim that the independent parliamentary budget office wants to test, but has been repeatedly stonewalled by multiple government departments -- Transport Canada included -- that refuse to disclose how and where they are slashing their budgets.

"There's a stark contradiction between the statements coming from the minister in the House, saying our first priority is the safety of Canadians, and how they manage those departments," Matthew Kellway, the NDP deputy transport critic, said an interview.

Improved safety during funding cuts is "entirely implausible," he said.

"While they're cutting, the issue they have to contend with is growing -- particularly in rail safety, where it's growing at exponential rates."

The Canadian Association of Petroleum Producers estimates that by 2016 the rail industry will move 700,000 barrels of western Canadian oil a day, up from less than 300,000 barrels in all of 2009.

"It is very difficult to believe a department can find efficiencies at a time when the transportation of dangerous goods, the transportation of oil, has increased by over 1,600 per cent in the last three years," said Liberal transport critic David McGuinty.

"If they have evidence to substantiate their claims that this is all about efficiencies, let them provide it."

Last February, a rail safety audit of Transport Canada found that "continuing budget reductions have had a major impact on the (Transportation Dangerous Goods) Directorate and it is most likely that new funding will be needed to manage the additional workload" associated with new, post-Lac Megantic rules on rail safety.

In fact, funding under the "transport of dangerous goods" did increase to $14.7 million last year, up from $12.7 million spent in 2012-13. Spending on the dangerous goods directorate averaged $13.9 million in the three previous years.

By way of comparison, the Conservatives budgeted $16.5 million last year, according to supplementary estimates, to advertise "responsible resource development," a program that includes new safety rules for the marine transport of oil, such as double-hulled tankers.

"We've been raising concerns about changes in the way that Transport Canada is moving for a number of years now," said Christine Collins, the national president of the Union of Canadian Transportation Employees.

"We've been raising concerns for the safety of the travelling public."

Collins, whose union represents 8,000 federal transport workers, including about 2,000 at Transport Canada, said the department's safety groups appear intent on hiring about 130 people in all by next spring.

However, retirements and poaching by the more lucrative private sector mean real employment gains are difficult, she added.

"At the end of the day, in rail safety and transportation of dangerous goods we'll be slightly above current numbers. But in civil aviation and marine, we will be struggling."