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The 13 Russians indicted by the US on charges of tampering with the 2016 election will "never" be extradited, Russian President Vladimir Putin said, while denying they acted on behalf of himself or Russia.

"Never. Never. Russia does not extradite its citizens to anyone," Putin said during an interview with NBC News.

Putin's comments underscore the challenges the US faces in prosecuting 13 Russian nationals and three Russian groups accused of using social media to sow seeds of discord among Americans during the election. The 37-page indictment detailed how Russians used stolen identities to pose as Americans on Facebook and Instagram, creating Facebook groups, buying divisive ads and posting inflammatory images.

"I know that they do not represent the Russian state, the Russian authorities," Putin said. "What they did specifically, I have no idea."

He challenged the US to provide "some materials, specifics and data," which Russia would then be "prepared to look at them and talk about it."

In an indictment released in February, US special counsel Robert Mueller and the Justice Department called out the Internet Research Agency, a group linked to Russian propaganda efforts across social media. Employees for the IRA created troll accounts and used bots to stage arguments and fuel political unrest during the 2016 campaign.

According to the indictment, the organization included hundreds of staffers dedicated to trolling online and had an annual budget into the millions.

The group allegedly controlled the Facebook accounts "Clinton FRAUDation," and "Trumpsters United," and the Twitter account "March for Trump." The agency also set up fake rallies at the same location for both sides of the political divide.

The US has no extradition treaty with Russia, and Putin's comments on extradition are in line with Russian law prohibiting Russian citizens from being handed over to foreign countries.

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