OTTAWA -- Liberal MPs have thwarted a bid by Conservatives to force Justin Trudeau's national security adviser to explain his assertion that rogue elements in the Indian government sabotaged the prime minister's trip to India last week.

The Liberals used their majority on the Commons' national security committee Thursday to block a Conservative motion asking that Daniel Jean be summoned to testify about his theory that factions in India were behind the furor over Jaspal Atwal, a convicted attempted assassin and one-time Sikh separatist extremist who wound up on the guest list for two events with Trudeau during the India tour.

Public Safety Minister Ralph Goodale, who was at the committee to discuss his department's spending estimates, also declined to discuss Jean's theory, telling Conservative MPs they were veering into classified territory that he's not at liberty to discuss.

He advised them to take their motion to the national security and intelligence committee of parliamentarians, a vehicle specifically created by the Trudeau government to allow MPs to probe classified matters.

However, that would guarantee Jean's explanation would never see the light of day. Members of that committee must obtain security clearance and swear an oath that they will maintain for the rest of their lives the confidentiality of the information they receive.

Following his committee appearance Thursday, Goodale was pressed to explain why Jean was able to brief reporters last week but can't do the same for MPs.

"MPs have a responsibility to pursue the whole issue and, in order for them to be able to do that, they need access to the full scope of classified information," he said.

It was during the media briefing that Jean suggested Atwal's presence during Trudeau's trip was arranged by factions within the Indian government who want to prevent Prime Minister Narendra Modi from getting too cosy with a foreign government they believe is not committed to a united India.

Goodale refused to specifically discuss Jean, who was outed as the source of the briefing by the Conservatives, but repeatedly said he trusts the advice of non-partisan, professional public servants, whom he said are "motivated by one thing only and that is serving the public interest of Canada." That's especially true, he said, of a public servant "from a diplomatic background and from a background that involves national security and public safety" -- which would describe Jean.

Atwal -- a B.C. Sikh convicted of trying to kill an Indian cabinet minister in 1986 -- attended a reception in Mumbai, where he was photographed with Trudeau's wife. An invitation to a later reception in New Delhi was rescinded as soon as news broke that Atwal was on the guest list.

B.C. Liberal MP Randeep Sarai has taken responsibility and apologized for issuing the invitation to Atwal and Trudeau has accepted his resignation as chair of the Liberals' Pacific caucus.

Goodale was pressed to explain how both Sarai and rogue factions in the Indian government can be simultaneously held responsible for the Atwal fiasco. He pointed to a newspaper column that cited an anonymous security official who noted it was the Indian government that took Atwal off its blacklist for entering the country, which set the stage for Sarai -- out of ignorance, or naivete, or both -- to issue the invitation.

As he made his way to the elevator following his committee appearance, being peppered with questions from reporters along the way, Goodale encountered Sarai, who pushed through the throng of reporters and ended up getting on the same elevator. Asked if he'd been working with rogue factions in India to undermine Trudeau's trip, Sarai said tersely: "No."

Trudeau, in Montreal to promote his government's federal budget, also continued to face questions about the affair Thursday. And even as he appeared to lay the blame for the matter squarely at the feet of Sarai, he too continued to lend credence to the theory put forward in Jean's briefing.

"The individual in question never should have received an invitation, and the member of Parliament responsible for extending that invitation has taken responsibility and apologized for it," Trudeau said.

"On top of that, I continue to trust and support our national security agencies and officials, and when they highlight that there are concerns around a particular issue, I trust them and I believe them."

The Indian external affairs ministry has rejected Jean's theory as "baseless and unacceptable." But a leading Sikh politician in India, whose party is allied with Modi's party, has echoed the assertion that the elements in the Indian government worked to undermine Trudeau's trip.