WASHINGTON/SAN FRANCISCO (Reuters) - Some of the ads bought by Russians on Facebook last year promoted events during the U.S. presidential campaign, Facebook Inc said on Tuesday, indicating that alleged meddling ahead of the 2016 election went beyond social media.

FILE PHOTO - The Facebook logo is displayed on their website in an illustration photo February 1, 2017. REUTERS/Regis Duvignau/Illustration/File Photo

Facebook said in a statement that its takedown of what the company last week called Russian-affiliated pages included shutting down “several promoted events.”

Facebook declined to provide details of the promoted events.

Facebook, the world’s largest social network, said last week that an operation likely based in Russia had placed thousands of U.S. ads with polarizing views on topics such as immigration, race and gay rights on the site during a two-year period through May 2017.

U.S. Senator Mark Warner on Tuesday said he was “disappointed” in Facebook for failing to present the latest information during a briefing last week with staff of the Senate Intelligence Committee, which is investigating allegations of election interference.

“We’re seeing more evidence of additional ads and how they are used to manipulate individuals,” Warner, the committee’s vice chairman, told reporters.

Facebook said it will continue working with U.S. authorities as necessary.

Russian President Vladimir Putin has denied that his government interfered with the U.S. election, in which Republican Donald Trump defeated Democrat Hillary Clinton.

The Daily Beast, the news website that first reported on the promoted events posted on Facebook, said one advertisement promoted an anti-immigrant rally in Idaho in August 2016.

The rally was hosted by a Facebook group called “Secured Borders,” which was a Russian front and is now suspended, according to the Daily Beast.

Some 48 people on Facebook expressed an interest in the Idaho event and four said they went, according to a copy of the event page archived by Google’s search engine.

The Campaign Legal Center, a Washington nonprofit that advocates for more transparency in elections, on Tuesday sent a letter to Facebook Chief Executive Mark Zuckerberg asking that the company publicly release the content of the alleged Russia-linked political ads.

“Releasing those advertisements could allow the country to better understand the nature and extent of foreign interference with our democracy,” the center’s president, Trevor Potter, wrote.

Facebook said in response to the letter: “Federal law and ongoing investigations limit what we can share publicly.”

The company has turned over information about the ads to Robert Mueller, the special counsel investigating alleged Russian interference, a source has said.