But opposition MPs continued to press the Conservative government for answers Wednesday about the mysterious doctor from Sierra Leone who now lives in the Bahamas, where he runs a cancer clinic.
Interim Liberal Leader Bob Rae called Wednesday for a federal inquiry, while the New Democrats and Greens demanded that Porter be stripped of his privy councillor status.
Five years ago the Conservatives appointed Porter — a medical doctor and cancer specialist — to the Security Intelligence Review Committee, which keeps an eye on the Canadian Security Intelligence Service and investigates complaints about CSIS.
Porter became chairman of the review committee in 2010 but quit abruptly the following year amid questions about his dealings with a notorious international lobbyist on an aid-for-development project in his African homeland.
Quebec's anti-corruption squad recently issued an arrest warrant for Porter and several others on fraud-related charges linked to a McGill University hospital mega-project in Montreal.
The intelligence review committee looked at the secret material handled by Porter during his time at the watchdog and turned up no cause for concern, said Adam Green, a committee spokesman.
"None of the documents that came across his desk have anything to do with anything that's out there in terms of the allegations against him," Green said.
"Internally, we have no indication that there was any security breach."
Review committee members serve part-time and see classified material only at the committee's Ottawa offices, Green noted.
"They are not here day-to-day, and they certainly do not go walking around at CSIS sitting at desks and going through databases or anything like this," he said.
"So basically we can track every document that any of our members or chairs were provided when they were at SIRC."
In the House of Commons, Rae said the Porter affair, and the recent conviction of a naval officer for selling secrets to Russia, point to the need for a national inquiry.
Prime Minister Stephen Harper delivered the government's now-stock answer, that the allegations against Porter have nothing to do with his past duties at the review committee.
Rae said Wednesday he wants to know more about how Porter — someone with no experience in political or security matters — got appointed to the spy watchdog in the first place.
"I think we need to know the circumstances under which his name came forward. We have no indication of that from the prime minister at all. This is not somebody who is being appointed to some low-level job," Rae said outside the House.
"Who were the people who thought that this was a good idea? And who would benefit from such an appointment? I continue to have serious questions about the entire process."
Letters have surfaced showing the Bloc Quebecois advised Harper against both naming Porter to the committee and elevating him to chairman.
Gilles Duceppe, then the Bloc leader, cited media reports of numerous problems during Porter's previous tenure at a Detroit medical centre. Duceppe also expressed concern about Porter's impartiality, given suggestions he was friendly with U.S. leaders George Bush and Dick Cheney, who had defended mistreatment of prisoners in the fight against terrorism.
Review committee members are made privy councillors for life, meaning they must swear an oath of allegiance to the Queen and promise to keep confidential matters secret.
Green party Leader Elizabeth May called Wednesday for Porter's removal from the Privy Council, calling his appointment to the committee and later rise to chairman "perhaps the most shocking failure of judgment and due diligence in Canadian history."
The Canadian Press reported in January that the Harper government quietly introduced strict new security vetting for nominees to the spy watchdog following Porter's November 2011 resignation.
Appointees to the committee now must be security cleared to the top secret level, a rigorous process involving multiple reference checks.