Ward Elcock, the security chief for the upcoming G8 and G20 summits, says the high price of the security operation will be "comparable" to previous meetings by those groups.

"Our security practices are the same as other countries that attend the G8 and the G20 on a regular basis," Elcock said on CTV's Power Play. "And I would expect that, if you actually could find an apple-to-apple comparison, you would find that our security costs are actually pretty comparable."

The combined price of the security operation to protect the G8 meeting in Huntsville, Ont. on June 25 and the G20 meeting in Toronto on June 26-27 now sits at an estimated $930 million.

By comparison, the reported cost of the G20 summit last year in Pittsburg was $18 million. In London, England, the price tag hit $30 million.

But Elcock, who is a former director of Canadian Security Intelligence Service, suggested that the actual cost for previous G20 meetings may be higher than reported.

"I think Canada is one of the rare countries that has actually been transparent about the security costs," he said. "For example, CSIS costs will be there as an item in the list. In many countries they don't publish the security costs associated with their intelligence agencies."

Elcock added that hosting two separate summits has added to the security expenses.

Opposition parties disagree.

New Democrat MP Olivia Chow, who represents the Toronto riding where the G20 summit will be held, called the spiraling cost of the two meetings "obscene."

She then repeated her party's call for Parliamentary Budget Office Kevin Page to audit the security budget for the summits.

"As a local member of Parliament, I have had no briefing. There is no transparency as to how the money is being spent," she said.

"Think of what $1 billion can do for Canadians," she added. "Full accounting, so that we know how that money is being spent, is very important."

Page is considering whether to look into the security costs, after receiving a formal request from the NDP.

Public Safety Minister Vic Toews said he "would welcome" Page to review the security budget for the events.

The Liberals, for their part, have asked Auditor-General Sheila Fraser to launch a similar review of the security spending.

In the last federal budget, $179 million was earmarked for security at the G8 and G20, the Liberals wrote in a letter to Fraser.

"We have the government here who only just very recently said this was going to cost a fraction of what we're now hearing," said Liberal public works critic Martha Hall Findlay. "Why were we being told it was so little only now to be told that it's so much?"

"I think we owe it to Canadians to have the government review seriously what it is that they're expecting to do from a security perspective, and really determine is it in fact really more than is necessary."

The Conservatives have steadfastly defended the increasing cost, a large portion of which will cover overtime for security personnel.

"The reality is, in a post-9/11 environment, security will not come cheaply," Transport Minister John Baird said in the House of Commons.

With files from The Canadian Press