About 10 million people in the United States saw politically divisive ads on Facebook that the company said were purchased in Russia in the months before and after last year's U.S. presidential election.
Facebook said in a statement on Monday that it used modeling to estimate how many people saw at least one of the 3,000 ads. It also said that 44 percent of the ads were seen before the November 2016 election and 56 percent were seen afterward.
The ads have sparked anger toward Facebook and, within the United States, toward Russia since the world's largest social network disclosed their existence last month. Moscow has denied involvement with the ads.
Facebook Chief Executive Mark Zuckerberg has outlined steps that the company plans to take to deter governments from abusing the social media network.
Earlier on Monday, Facebook said in a separate statement that it planned to hire 1,000 more people to review ads and ensure they meet its terms, as part of an effort to deter Russia and other countries from using the platform to interfere in elections.
The latest company statement said that about 25 percent of the ads were never shown to anyone.
For 99 percent of the ads, less than $1,000 was spent, said Elliot Schrage, Facebook's vice president of policy and communications. The total ad spend was $100,000, the company has said.
Still, he said it was possible Facebook would find more Russia-linked U.S. ads as it continues to investigate.
Facebook is working with others in the tech sector, including Twitter Inc and Alphabet's Google, on investigating alleged Russian election meddling.
Like other companies that sell advertising space, Facebook publishes policies for what it allows, prohibiting ads that are violent, discriminate based on race or promote the sale of illegal drugs.