Justin Trudeau says he's received what he calls a "great" report from former Liberal cabinet minister Anne McLellan on the SNC-Lavalin affair.

But the prime minister won't make it public until federal ethics commissioner Mario Dion releases his own report into the explosive affair that rocked the government last winter and sent Liberal popularity on a downward slide from which the party has not yet fully recovered.

Dion's office won't comment on the status of his investigation but Liberal insiders privately expect the report will be released in early September — just as the campaign for the Oct. 21 election moves into high gear.

Trudeau is likely hoping to blunt the impact of a potentially damaging report from the ethics commissioner by releasing McLellan's report at the same time.

He appointed her as a independent adviser to analyze and make recommendations on questions that arose out of the SNC-Lavalin affair, including whether the roles of minister of justice and attorney general should be separated.

The affair revolved around an allegation by former attorney general Jody Wilson-Raybould that she was improperly pressured by the Prime Minister's Office to halt a criminal prosecution of the Montreal engineering giant, as allowed by law.

Trudeau has maintained that no one did anything wrong and has attributed the controversy to a breakdown in trust between his staff and Wilson-Raybould, who quit cabinet in February, followed by her friend and ally, Jane Philpott. Both former ministers are running for re-election as independent candidates.

McLellan was to have reported back to Trudeau by June 30. In a statement Tuesday, deputy Conservative leader Lisa Raitt questioned why Trudeau has not yet released McLellan's recommendations and put it down to another example of "just how far (Liberals) will go to cover up the truth."

Asked about the report later Tuesday at an event with Toronto Mayor John Tory, Trudeau acknowledged he's received it and said he's given it to Dion.

Liberals, he said, recognize the importance of looking at the possibly incompatible roles played by someone who is both justice minister, involved in political and policy decisions of government, and the attorney general, who is supposed to exercise independent, non-partisan judgment about prosecutions.

"That's why we were very pleased to have a great report written by Anne McLellan. We have provided that report to the ethics commissioner to allow the ethics commissioner to finish his own investigation and we will be releasing the report at the same time as the ethics commissioner makes his report public," Trudeau said.

Raitt scoffed at the notion that McLellan was "independent," noting that she was scheduled to be a headliner at a Liberal party fundraiser at the time she was appointed to look into the SNC-Lavalin fiasco. Raitt accused Trudeau of trying to distract Canadians from his government's political interference in the justice system by launching McLellan's study of the dual justice minister/attorney general role.

Trudeau also tasked McLellan with analyzing the "operating policies and practices across the cabinet, and the role of public servants and political staff in their interactions with the minister of justice and attorney general of Canada.”