Sandberg and others from Facebook appeared before USA congressional panels looking into reports of Russian interference in the election.
The company disclosed last month that it found ads linked to fake accounts - likely run from Russian Federation - that sought to influence the election.
USA lawmakers have said they planned to release the ads placed on Facebook once any personal information on users is removed.
Facebook has admitted it shouldn't have allowed fake Russian accounts to fund ads supporting Trump in the USA election and will do everything in its power to help authorities get to the bottom of the alleged election interference campaign.
Facebook handed over about 3,000 of the ads to congressional investigators after the company learned that some of the ads had been reportedly purchased by a Russian troll company to sow more divisions among Americans. She said Facebook hopes to "set a new standard in transparency in advertising".
"The thing about free expression is that when you allow free expression, you allow free expression", Sandberg said. Representatives from Facebook, Google and Twitter are expected to testify about Russian influence at hearings before the Senate and House intelligence committees on November 1. Sandberg is no stranger to Washington.
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Asked if that meant providing data on how ads were targeted to specific groups of people, Sandberg said Facebook was prepared to do so.
Sandberg said Facebook would provide additional material to investigators as needed to determine the level of foreign interference in the USA election.
Sandberg said it was important to protect "free expression" on Facebook and that if the Russian ads had been bought by legitimate accounts instead of fraudulent ones, many would have been allowed to run on the site.
Later Thursday, Sandberg met privately with members of the Congressional Black Caucus, where she was pressed on what the company is doing in response to its discovery that numerous ads pushed by Russian-linked accounts were aimed at sowing racial discord.
Sandberg's meeting with the caucus was just the latest stop in an apology tour launched after Facebook faced harsh criticism for denying, back tracking, then finally admitting the key role it played in Russia's disinformation campaign. Some of the ads showed white police officers beating black people, said the member, who spoke on condition of anonymity because the ads aren't yet public.
Besides discussing election meddling, the members also pushed for Facebook to improve diversity in its workforce, particularly in its upper management.
The chairman of the CBC, Cedric Richmond, also confirmed the report that Sandberg and the company would be working to add a minority to the board sometime soon. Two, including Sandberg, are women.