Special counsel and former FBI Director Robert Mueller obtained a search warrant that forced Facebook to hand over the ads it sold to a company known for pro-Kremlin propaganda, as well as information about them.
Facebook hasn't shared the same information with Congress, largely because of concerns about disrupting the Mueller probe, and possibly breaking US data privacy laws, the Journal said.
Representatives of Facebook previously told congressional investigators that, during the course of an investigation into the site's role in the 2016 election, it had discovered that a Kremlin-linked firm had bought $100,000 of ads between 2015 and 2017.
The Journal based its report on "people familiar with the matter".
Facebook didn't share that data with Congress partly amid concerns it might disrupt the Mueller probe and due to USA privacy laws, the people said, according to the report.
Facebook said it is cooperating with investigators and declined to comment further. Facebook policy dictates that it would only turn over "the stored contents of any account", including messages and location information, in response to a search warrant, some of them said.
Senate Intelligence Committee Chairman Richard Burr, Republican from North Carolina, said this week he wanted a "full accounting" of what happened given Facebook's own admission that Russians appeared to buy US$100,000 (RM419,200) in political ads in the USA past year, and has said a public hearing is more likely than not.
The Senate Intelligence Committee also hasn't ruled out subpoenaing Facebook officials to publicly testify about how Russian Federation may have used the social media platform to influence the 2016 election, a person familiar with the investigation told the Journal. It is even possible that unidentified ad buys may still exist on the social media network today. He has been discussing next steps with the committee's ranking Democrat Mark Warner of Virginia.
Facebook is launching the program in Canada as internet companies seek to fend off criticism they are not doing enough to thwart online interference with elections and politics.
Lawmakers are concerned not just with the last year's activities but with preventing future efforts to target American elections and those of allies.