NDP Leader Jack Layton is calling on the information commissioner to investigate the censoring of documents and whether there has been government interference. (Pawel Dwulit/Canadian Press)

Opposition parties are calling on the information commissioner to investigate how the government censors records and whether there has been any political interference from the Prime Minister's Office.

"There's been a pattern of delay and obstruction with this government that should worry Canadians with regard to access to information," NDP Leader Jack Layton told reporters in Ottawa on Tuesday.

The request from both the Liberals and NDP follows news that a top political aide to the Public Works Department's minister overruled bureaucrats and had forbidden the release of a sensitive report to The Canadian Press.

"That’s why the information commissioner must investigate all instances of Conservative interference and order the public release of all politically censored documents," Liberal Treasury Board critic Siobhan Coady said on the party's website on Monday.

Layton said the access-to-information laws are laws, not just guidelines, and the prime minister needs to say those laws will be upheld.

During his news conference, Layton showed two different versions of the same memo he said he received from two government agencies — the Defence Department and the Justice Department.

Layton said one memo had some lines blotted out, while the other had a lot of the information deleted.

"You've got to ask yourself what is going on here. I think we've got to get to the bottom of it. A free society requires access to the facts. That's fundamental," Layton said. "And a government can't simply say we're going to protect ourselves by building walls around the truth. That's not right."

Censored report handed over

Last July, a Public Works Department bureaucrat was ordered to retrieve a 137-page report from the mailroom after an aide to then Public Works Minister Christian Paradis discovered the document was being sent to The Canadian Press.

The news agency requested the report, an accounting of the government's real-estate portfolio, under the Access to Information Act. But Paradis aide Sebastien Togneri sent a terse email to officials July 27 demanding that they "unrelease" it.

The bureaucrats were ordered to provide only a single chapter of the report, amounting to 30 pages.

Officials eventually handed over a censored report 82 days later than the deadline under the law.

The information commissioner is investigating the incident.

Dimitri Soudas, spokesman for the prime minister, told The Canadian Press that when it comes to Access to Information, "due diligence is and should be done by public servants and not political staff.

"The process … should be followed and respected by all…. It applies to everybody across government [including] political offices."

With files from The Canadian Press