WASHINGTON — Facebook chief operating officer Sheryl Sandberg said Tuesday that the social media giant takes the targeting of minority voters "incredibly seriously" and is working to "strengthen and advance civil rights on our service."

Her remarks, published in a Facebook post addressed to employees Tuesday morning and first reported by NBC News, come a day after the Senate intelligence committee released a pair of reports concluding that Russian agents at the Internet Research Agency used top social media services to aid President Donald Trump's 2016 campaign by trying to suppress the votes of African-Americans.

The Senate-commissioned reports "suggest that the IRA's efforts had a disproportionate impact on communities of color," Sandberg wrote. "We take this incredibly seriously, as demonstrated by the investments we’ve made in safety and security."

And, she added, "We need to do more."

Facebook has come under a wave of scrutiny in 2018 and now faces questions ranging from its handling of user data and the disclosure of security flaws to how it reacted to Russian incursions onto the social network and its subsequent efforts to combat the negative attention brought upon the company. That public relations effort has taken a toll on Sandberg, who has been the subject of growing criticism for the company's hiring of a conservative lobbying firm that gathered opposition research on billionaire philanthropist George Soros, who had emerged as a vocal Facebook critic.

Sandberg's post was published in conjunction with a nine-page update on a civil rights audit of Facebook being conducted by Laura Murphy, the former director of the American Civil Liberties Union's Washington legislative office.

Facebook has come under intense scrutiny on Capitol Hill, and across the country, because its platform — like those of other major social media companies — was weaponized to influence the last presidential election.

In February, Special Counsel Robert Mueller, who is investigating the Trump operation's ties to Russia, indicted more than a dozen suspected Russian agents on charges of defrauding the U.S by meddling in the election.

In conversations with civil rights advocates, Murphy wrote in her report, she found that they were "deeply alarmed" at the impact of ads run by the IRA on Facebook.

"They expressed concern that such ads encouraged racial and religious animus, attempted to suppress minority voter turnout, and particularly targeted communities of color and racial and ethnic minorities," Murphy wrote.

And, she added, "it is now clear that Facebook was slow to understand the IRA’s activities, a point the company has acknowledged."

Though the audit is ongoing, Murphy reported that she and her team have met with representatives of more than 90 groups to better understand and address concerns about issues including voter suppression, hate speech, encouraging diversity in the company's workforce and ensuring that artificial intelligence tools do not promote bias.

"The purpose of the audit is to ensure Facebook makes real and lasting progress in the area of civil rights and civil liberties," Murphy wrote.

Both she and Sandberg pointed to steps Facebook already has taken, including the audit, to devote resources and attention to the concerns of civil rights advocates and the sanctity of elections.

Murphy noted that in the run-up to November's midterm elections, the company enhanced its policy against spreading misinformation about voting — including the date of elections, false claims about long lines and poll closings, and threats of violence against voters — sent reminders to users about registration and election days, hired outside legal advisers to assist Facebook's policy and operations units, and created pathways for voters and officials to report misinformation.

"Given the complexity of the issues, implementation took longer than expected," she wrote, "but Facebook did make important changes prior to the U.S. midterm election."

During the midterms, Facebook established a physical "war room" at its Menlo Park, Calif., headquarters to put employees working to combat election-related problems in one place. The company also blocked more than 100 accounts over worries that they were linked to the IRA in the run-up to the midterms.

But Sandberg said Facebook hasn't finished its work in the civil rights arena.

"We know that we need to do more: to listen, look deeper and take action to respect fundamental rights," she wrote. "Laura’s report includes areas where we can and should do better — and we’re working hard to address these concerns."