Russian agents reportedly used a Facebook tool to target specific American voters in an attempt to influence their politics.

According to a Tuesday report in The Washington Post, the Russians used a Facebook tool known as Custom Audiences to target groups of Americans by gender, demographics, interests and geography.

The Post cited individuals knowledgeable with the probe into Russian attempts to interfere in the 2016 presidential election.

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The method of targeting has been used by United States political campaigns and American companies to convey messages to individuals who could be interested, the report said.

Facebook in a Tuesday update to a post describing the advertisements the company turned over to Congress said that 1 percent of the ads had utilized one kind of the Custom Audiences method.

“About 1% of the ads used a specific type of Custom Audiences targeting to reach people on Facebook who had visited that advertiser’s website or liked the advertiser’s Page — as well as to reach people who are similar to those audiences,” Facebook’s vice president of policy and communications, Elliot Schrage, said in the update.

“None of the ads used another type of Custom Audiences targeting based on personal information such as email addresses.”

News of the Russians' use of the Facebook tool to target users comes amid the controversy over the website’s political advertising during the 2016 campaign. Facebook admitted last month that Russians who were potentially linked to the Kremlin bought ads on the platform during the presidential race. The revelation angered liberal groups and lawmakers alike.

Facebook on Monday said approximately 10 million people viewed political ads that were purchased by Russian actors approaching the 2016 presidential election. The company’s numbers showed that 44 percent of the ads were viewed before the election, while 56 percent were viewed after the election.

The social media company on Monday also released more than 3,000 political ads purchased by Russian actors on its platform to congressional investigators.

The Senate Intelligence Committee, one of several congressional committees conducting a probe into Russia’s attempts to meddle in the United States election, last week invited Facebook to testify at an upcoming hearing that will evaluate how foreign actors possibly used social media companies to influence the election.