WASHINGTON (Reuters) - A U.S. senator on Wednesday said Russian internet trolls, seeking to polarize Americans, helped fuel a debate ignited by President Donald Trump over whether NFL players should have the right to kneel during the national anthem.

FILE PHOTO - U.S. Senator James Lankford (R-OK) smiles after he was ceremonially sworn-in by Vice President Joseph Biden in the Old Senate Chamber on Capitol Hill in Washington January 6, 2015. REUTERS/Larry Downing

The assertion, made by Republican James Lankford, comes as congressional investigators probing Moscow’s alleged meddling in the 2016 presidential election are focusing on how Russian agents used social media to spread divisive political content.

“We watched, even this weekend, the Russians and their troll farms, their internet folks, start hashtagging out #TakeAKnee and also hashtagging out #BoycottNFL,” Lankford, who sits on the Senate Intelligence Committee, said during a hearing on threats faced by the United States.

“They were taking both sides of the argument this weekend ... to try to raise the noise level of America and make a big issue seem like an even bigger issue as they are trying to push divisiveness in this country,” Lankford said.

Lankford did not provide evidence to corroborate his statement.

A Lankford aide said U.S. intelligence shared with senators showed that Russian troll operations relied on social media to meddle in U.S. issues going back to last year’s presidential election in an effort to divide Americans.

Such activity has also been occurring in Europe for years, the aide said.

A website built by researchers working with the Alliance for Securing Democracy, a bipartisan, transatlantic project to counter Russian disinformation, showed tweets promoting both sides of the football debate from 600 accounts that analysts identified as users who spread Russian propaganda on Twitter.

A Senate aide said the website was viewed as credible among congressional investigators.

Facebook this month revealed that suspected Russian trolls purchased more than $100,000 worth of divisive ads on its platform during the 2016 election cycle. Twitter is expected to privately brief the Senate panel on Thursday, and the House Intelligence Committee said Wednesday technology companies would testify about Russian interference in an open hearing next month.

Trump last week said that football players should be fired for kneeling during the national anthem. The players want to draw attention to what they say is social and racial injustice.

U.S. intelligence agencies have concluded that Russia orchestrated a multi-pronged cyber offensive on the 2016 election to discredit Democratic candidate Hillary Clinton and help Trump, a Republican, win.

Russia denies seeking to influence the U.S. election, and Trump has dismissed claims of collusion as fake news.

(This version of the story has been refiled to remove extraneous word “layers” in paragraph 11)