OTTAWA - A former Tory aide accused of interfering in an access-to-information request is firing back at his critics.

A lawyer for Sebastien Togneri has sent a letter to three lobby groups, warning them to back off from making "false and defamatory" statements.

The Sept. 1 missive takes issue with a letter sent to the chair of a House of Commons committee by the Canadian Taxpayers Federation, Newspapers Canada and the B.C. Freedom of Information and Privacy Association.

The three groups asked the committee to review the Access to Information Act after the RCMP announced in August that it was dropping its investigation into Togneri because a criminal investigation was "unwarranted."

The Togneri case set off a political firestorm when it was revealed by The Canadian Press that he had ordered the "unrelease" of a sensitive document that the Public Works Department was set to provide to the news agency after a request under the Access to Information Act.

Togneri at the time was a senior aide to then-Public Works minister Christian Paradis.

Canada's information commissioner launched a year-long investigation that concluded early this year that Togneri had interfered with the release of a record, even though he had no legal authority to do so.

Suzanne Legault recommended the RCMP investigate the matter, with reference to Section 67.1 of the Access to Information Act, which imposes fines and jail time to anyone who even counsels the withholding of documents.

Public Works Minister Rona Ambrose then called in the Mounties, who later dropped their preliminary probe.

The three watchdog groups asked Parliament to find out why the RCMP ended its investigation into Togneri, who once appeared before a Commons committee to acknowledge he had made a "mistake."

"The RCMP decision to abandon this investigation is extremely troubling," John Hinds, president of Newspapers Canada, said in a new release at the time.

"It appears to leave people most likely to interfere with ATI (Access to Information) requests above the law, and that just cannot stand."

But Togneri's lawyer played down the "mistake," saying in his Sept. 1 letter that his client never interfered with the release of the document.

"Mr. Togneri simply hastily questioned why a lengthy document was being released when the information actually sought was contained in only one short section of it," wrote Paul K. Lepsoe of the Ottawa firm Lavery, de Billy.

"He never intended or instructed that information actually sought should not be released."

Scott Hennig of the taxpayers' group rejected Lepsoe's letter, which is a first step under Ontario's Libel and Slander Act.

"Their claim is total B.S. and they likely know it," he wrote on the organization's website.

"Mr. Togneri should have done his homework first. It wouldn't have taken much digging to realize the CTF isn't easily intimidated. We will not back off just because you pay a lawyer to send us a strongly-worded letter.

"In fact, sending us such a letter with such weak arguments, makes it clear to us you have no intention of actually filing suit and that you are just trying to intimidate us into silence. Either that or you are trying to bog us down and make us incur lawyer costs that you are guessing we cannot afford.

"Either way, you guessed wrong."

Under Ontario law, Togneri now has three months to file a defamation suit.

The RCMP's abandoned investigation is the second time the Mounties have declined to lay charges in a high-profile case involving Section 67.1. Last fall, officers decided no charges were warranted after a two-year investigation into the deliberate destruction of emails at the National Gallery of Canada.

Legault also found clear evidence in that case that public servants were counselled to destroy records.

No one has ever been charged under Section 67.1, which was added to the act in 1999 after scandals in which defence and health records had been destroyed to avoid embarrassing revelations.

The Commons access committee, which meets Thursday, is chaired by an opposition member, the NDP's Nathan Cullen, who has said he wants to examine the case.

Last month, Togneri welcomed the RCMP decision for "clearing me of any wrongdoing." He called Legault's investigation of him "grandstanding."

Togneri left government in 2010, and was removed from the federal election campaign of a Tory candidate in Edmonton in April when his role there became public.

Legault has launched other investigations of alleged political interference in access-to-information at Public Works, Foreign Affairs and National Defence, based on specific allegations brought to her attention. The reports are expected over the next year.

Her office is also conducting a self-initiated investigation into systematic interference in the access-to-information process at eight major departments: National Defence, Public Safety, CIDA, the Privy Council Office, Health Canada, Heritage Canada, Natural Resources Canada and the Canada Revenue Agency. That report is expected sometime next year.