TORONTO -- A former federal cabinet minister told an Ontario court Thursday he had been warned that there was no way of knowing whether information in a national security certificate used to arrest accused terrorist Mohamed Mahjoub was obtained through torture.

Former public safety minister Stockwell Day said he signed five security certificates in late February 2008 -- including Mahjoub's -- after reviewing a "voluminous" amount of documents and "numerous" discussions with both intelligence and border officials.

Testifying by videolink from Vancouver, Day said he was confident in the information even though the former head the Canadian Security Intelligence Service had given him a memo stating it was "difficult, if not impossible" to determine the source of the information, particularly because some of it had come from countries with a reputation of using torture.

"I was satisfied with all of the information before me to date," he told a Federal Court judge in Toronto.

"The security certificate needed to be signed for ongoing restraint on Mr. Mahjoub, for the protection of Canadians."

The federal government is trying to deport the Egyptian-born man using a national security certificate -- a rarely used immigration tool for removing non-Canadians considered a risk to the country.

It claims that Mahjoub, 52, was a high-ranking member of an Islamic terrorist organization with links to Osama Bin Laden.

It also alleges the father of three falsified documents when he first arrived in Canada as a refugee in 1995.

He was interviewed by CSIS on six occasions between August 1997 and March 1999, each time denying any involvement in Islamic extremism.

Mahjoub was arrested in June 2000 based on secret evidence but CSIS had to start over after the Supreme Court of Canada ruled seven years later that the certificate process was unconstitutional.

For the past 12 years, he has been either detained or placed under strict house arrest despite not being charged with a crime.

During hours-long cross-examination by one of Mahjoub's lawyers, Yaver Hameed, Day frequently replied "I can't recall."

At one point, Day explained that it had nearly five years since he signed those certificates.

However, he told the court he was confident of the accuracy of the information given to him by CSIS officials.

"My approach was to do all I could, alongside with what I was being presented to ascertain whether there was a sufficient level of confidence to come up with a decision to reflect the accuracy of the material and protection of Canadians," said Day.

The former minister said that during his time with the public safety portfolio, he always tried to ask numerous questions and saw himself as a "hands-on" minister.

"My position was that I wanted full disclosure," he testified. "I wanted total transparency. I wanted no surprises."

Day told the court he was aware that CSIS and the Canada Border Services Agency had for years been intercepting all of Mahjoub's phone calls, including communications between him and his lawyer which were under solicitor-client privilege.

The majority -- if not all -- of the information gleaned from those recorded phone calls have since been destroyed by CSIS.

Lawyer Paul Slansky, said they are trying to show that Day did not practice due diligence when he renewed the security certificate because he did not rely on the physical evidence, only summaries.

Mahjoub, on release from prison, sat in the front row of the courtroom and could be seen shaking his head and scoffing a number of times during Day's testimony.

Flanked by supporters outside the courthouse, Mahjoub accused the former minister of lying when he said he didn't remember many particulars about the case.

"Most of the time I have to laugh because if he can't recall, if he can't answer the question, it means to me he hides the truth," he said.

Three of the five men, including Mahjoub, are still subject to the national security certificates. The certificates for two others had been quashed by the courts.

The hearing continues in Federal Court Sunday, with videolink testimony from witnesses in Mahjoub's home country of Egypt.