Russian operatives reportedly used Facebook to organize rallies and protests on American soil during the election season. Dan Kitwood/Getty Images

Russian operatives reportedly used Facebook's Events feature to remotely organise and promote political protests in the US, including an anti-immigrant, anti-Muslim rally in Idaho last year. The social media giant said it "shut down several promoted events as part of a takedown" last week involving "Russian-affiliated pages",the Daily Beast first reported Monday (12 September).

The company revealed last week that an operation likely linked to Russia bought $100,000 worth of political ads on its site during the 2016 US presidential campaign with polarising views on key issues such as immigration, gay rights and race. The content was likely seen by an estimated 23-70 million people on the popular platform.

Facebook did not offer further details on the events but said they were promoted with paid ads.

The Daily Beast reported that one event announced the anti-immigrant protest in August 2016 that reportedly focused on Twin Falls, a rural town that has been known to welcome refugees for decades.

"Due to the town of Twin Falls, Idaho, becoming a centre of refugee resettlement, which led to the huge upsurge of violence towards American citizens, it is crucial to draw society's attention to this problem," the event notice for the three-hour protest read. "We must stop taking in Muslim refugees! We demand open and thorough investigation of all the cases regarding Muslim refugees! All government officials, who are covering up for these criminals, should be fired!"

The event titled "Citizens before refugees" was hosted by a group called "SecuredBorders", an anti-immigration community that was later revealed to be a Russian front in March, the news outlet reported.

About 48 people on Facebook expressed an interest in the event while four said they went. The Facebook page had 133,000 followers before Facebook closed it in August.

It is still unclear how many similar events were created using Facebook's events management tool.

Democratic Senator Mark Warner, a top lawmaker on the Senate Intelligence Committee, said he was "disappointed that Facebook didn't come forward with this information about the Russians pushing people to anti-immigration rallies".

"That somehow that was something they didn't think was relevant, which is again why I think this is the tip of the iceberg. There's going to be, I think, much more," Warner said on Tuesday. "I question whether Facebook has put near the resources they need into getting us all the facts."

He added that he has been frustrated with Facebook's limited disclosures on Kremlin-linked groups exploiting its platform to influence US politics and the 2016 elections.

The Senate Intelligence Committee is one congressional group currently investigating allegations of Russian interference in the November elections last year and possible ties between President Donald Trump's team and the Kremlin.

US intelligence agencies assessed with "high confidence" in January that Russian President Vladimir Putin ordered a complex "influence campaign" involving cyberattacks and disinformation campaigns to undermine American democracy, hurt Hillary Clinton's chances and help Trump win the vote. The Kremlin has dismissed the allegations and denied any involvement in the DNC hack.

In a letter to Zuckerberg, the Campaign Legal Center - a Washington-based non-profit that advocates more transparency in elections - has urged the firm to publicly disclose the content of the alleged Russian-linked political ads.

"Federal law has long recognised that American elections belong to Americans. It is illegal for any foreign national to spend money to influence American voters as they participate in the process of democratic self-government," CLC President Trevor Potter wrote in the letter. "Releasing those advertisements could allow the country to better understand the nature and extent of foreign interference with our democracy."

In response, Facebook said: "Federal law and ongoing investigations limit what we can share publicly." Reuters reports that the company has already turned over information regarding these ads to Robert Mueller, the special counsel heading the Russia probe.