The political scandal erupted after The Globe and Mail released an incriminating report that suggested that members from the PMO tried to pressure former Attorney General and Justice Minister Jody Wilson-Raybould into interfering in a criminal prosecution against the Montreal construction and engineering giant.
"We welcome the ethics commissioner's investigation", he told reporters in Burnaby, B.C., where he was stumping with the Liberal Party candidate in the February 25 byelection.
This is the fifth ethics investigation involving the Trudeau cabinet, which has been in office for less than four years.
The investigation was launched after Canada's Conflict of Interest and Ethics Commissioner, Mario Dion, agreed to the investigation request from the federal NDP. "At no time did I or my office direct the current or previous attorney-general to make any particular decision in this matter", said the Prime Minister.
It had hoped that it could come to a remediation agreement with prosecutors that would be an alternative to trial. A few months after that decision, she was moved from the attorney general's office to become the new minister of veterans affairs.
Even though the Prime Minister has denied the allegations, pressures have mounted for an investigation into the matter. "Canadians deserve better", said Charlie Angus, the party's ethics critic, in a written statement.More news: Seventeen killed in massive fire in central Delhi Hotel
SNC-Lavalin was charged with paying out $48 million in bribes to Libyan officials in the decade leading up to the NATO-led overthrow of Muammar Gaddafi's government in 2011, payments meant to influence government decision-making, though the company was also charged with defrauding Libyan companies of about $130 million.
Shortly after the Globe and Mail report, the Prime Minister denied the allegations, calling the story false.
He also wouldn't address calls from the Opposition for the government to waive solicitor-client privilege for his predecessor.
"But there is a line that can not be crossed - telling the attorney general what a decision ought to be".
Lametti was tightlipped with reporters at an event in Ottawa on Monday, but, speaking to CTV's Question Period on Sunday, he left the door open to granting SNC-Lavalin the deal that the Globe reports Wilson-Raybould refused to pressure the PPS to offer.
However, Wilson-Raybould was not in attendance at the event, despite representing a neighbouring riding.More news: Oops: Ardern admits admin error caused China flight U-turn
"In our system of government, of course, her presence in cabinet should actually speak for itself".
The Liberal government maintains that while discussions on the matter took place with Wilson-Raybould, she wasn't pressured or told to issue a directive to the prosecutor.
On Wednesday, the House justice committee will meet to review a request from the opposition parties that the committee investigate the allegations.
New Brunswick MP Wayne Long says in a statement posted to social media that he was "extremely troubled" when the allegation surfaced last week and nothing he has heard since has made him feel less unsettled. Long is not a member of the justice committee, however.
"We urge Mr. Trudeau's team to stop trying to discredit Ms. Wilson-Raybould and to commit to fully cooperate with the Ethic Commissioner's investigation".More news: Teenager with anti-vax mum gets vaccinated on his 18th birthday