Social media giant Twitter says it has provided U.S. congressional investigators with a "roundup" of ads from accounts used by Russia's state-sponsored television network RT.

The company says in a blog post that RT spent $274,100 on ads targeted to markets in the U.S. during 2016. Twitter provided the ads to investigators during closed-door meetings Thursday with the staff of the Senate and House intelligence committees.

The committees have been investigating Russia's interference in the 2016 presidential election and any possible co-ordination with Trump associates. They have specifically been looking at Twitter and Facebook, and their roles in the spread of misinformation and propaganda during the election.

Twitter says the ads it provided came from three handles used by RT. Most tweets from the accounts promoted news stories.

The closed-door meetings lasted several hours. The executives included attorney Elizabeth Banker; Emily Horne, global policy communications director; Carlos Monje, the company's director of public policy and philanthropy and Colin Crowell, a vice-president of public policy, government and corporate philanthropy.

Trump Russia Probe Twitter

Twitter's Emily Horne, left, global policy communications director, Carlos Monje, the public policy and philanthropy director, and Colin Crowell, head of global public policy, enter the closed door meeting with the House Intelligence Committee on Capitol Hill, Thursday in Washington. (Alex Brandon/Associated Press)

The meetings come after similar briefings from Facebook earlier this month. The House and Senate panels have invited both tech giants, along with Google, to appear at public hearings this fall.

Unlike Facebook, which has said phoney accounts on its platform attempted to stir up divisiveness in the election, Twitter had remained mostly silent. The two social media companies have different types of platforms, as Twitter allows users to register anonymously and has more public accounts than Facebook.

Virginia Sen. Mark Warner, the top Democrat on the Senate intelligence panel, said Twitter has "never tried to prevent fake accounts, use of bots." Comparing the company to Facebook, he said, "They don't deny they have allowed more anonymity. So they've got a different business model, we've got different questions for them."

Still, Warner said, the investigation is ultimately up to how people manipulated both of those platforms.

"People deserve to know," Warner said.

Challenges tracing intruders

Twitter, Facebook and Google haven't yet said whether they will accept the invitations to testify publicly before both intelligence committees. The House intelligence committee is planning to hold a hearing in October and the Senate intelligence committee has invited witnesses to appear on Nov. 1.

The companies have some incentive to comply, as Warner and Minnesota Sen. Amy Klobuchar have said they are preparing legislation that would enhance transparency for online political ads and require social media companies to keep a public file of election ads and communications. The bill would also ask companies to "make reasonable efforts" to ensure that election ads are not purchased directly or indirectly by a foreign national.

Warner said it's his "hope and expectation" that the companies would work with him on the legislation, which he called "probably the lightest touch possible."

Congress so far has been reluctant to regulate social media companies. But Warner and Klobuchar started working on the legislation as Facebook acknowledged that the hundreds of phony Facebook accounts, likely run from Russia, spent about $100,000 US on ads aimed at stirring up divisive issues such as gun control and race relations during the 2016 campaign.

Zuckerberg: 'We can make it much harder'5:43

Facing pressure from lawmakers and the public after that original announcement, Facebook CEO Mark Zuckerberg said last week that the company will provide congressional investigators with the contents of 3,000 ads bought by a Russian agency, while also pledging to make political advertising on its platform more transparent.

"I don't want anyone to use our tools to undermine democracy," Zuckerberg said in a Facebook video and wrote in an accompanying post. "That's not what we stand for."

On Wednesday, a Republican member of the Senate intelligence panel said Russian internet trolls are exploiting the controversy over NFL players kneeling during the national anthem to stir up divisions in the United States.

Sen. James Lankford of Oklahoma said paid social media users, or "trolls," were hash-tagging "take a knee" and "boycott NFL" to amplify the issue.