Washington (CNN) Sen. Bernie Sanders said Friday that his campaign was briefed about Russian efforts to help his presidential campaign, intensifying concerns about the Kremlin's role in the US presidential race.

It remains unclear how Russia is attempting to help Sanders, according to The Washington Post, which first reported the effort. The revelation comes a day after it was reported that the US intelligence community believes Moscow is taking steps to help President Donald Trump win and at a time when Sanders is emerging as the Democratic front-runner

Speaking to reporters in Bakersfield, California, Friday afternoon, Sanders confirmed that his campaign was briefed about the Kremlin's efforts about a month ago and condemned Russia's attempts to interfere in US elections.

"It was not clear what role they're going to play. We were told that Russia, maybe other countries, are going to get involved in this campaign, and look, here's the message to Russia: stay out of American elections," Sanders said.

"And what they are doing, by the way, the ugly thing that they are doing, and I've seen some of their tweets and stuff, is they try to divide us up. That's what they did in 2016 and that is the ugliest thing they are doing -- is they are trying to cause chaos, they are trying to cause hatred in America."

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