Thirteen Russian nationals and three Russian companies have been indicted for interfering in the 2016 US presidential election through social media propaganda.

The indictment, released yesterday by the office of US Special Counsel Robert Mueller, said, the accused, through their actions, wanted to "spread distrust towards the candidates and the political system in general".

According to the indictment, the Russians created hundreds of social media accounts on Facebook, Instagram, and Twitter, making it appear that the accounts were controlled by persons within the US.

To hide the Russian origin of their activities, the Russians allegedly purchased space on computer servers located within the US in order to set up a virtual private network.

The accused posed as politically and socially active Americans, advocating for and against particular political candidates. They established social media pages and groups to communicate with unwitting Americans.

They also purchased political advertisements on social media and used stolen or fictitious American identities, fraudulent bank accounts, and false identification documents.

Deputy Attorney General Rod J. Rosenstein said the indictment served as a reminder that people are not always who they appear to be on the Internet.

"The indictment alleges that the Russian conspirators want to promote discord in the United States and undermine public confidence in democracy. We must not allow them to succeed," said Rosenstein.

According to the allegations, twelve of the individual defendants worked at various times for Internet Research Agency (IRA), a Russian company based in St. Petersburg.

The other individual defendant, Yevgeniy Viktorovich Prigozhin, funded the conspiracy through companies known as Concord Management and Consulting LLC, Concord Catering, and many subsidiaries and affiliates.

The IRA allegedly operated through Russian shell companies. It employed hundreds of persons for its online operations with an annual budget of millions of dollars.

In 2014, the agency established a "translator project" to focus on the US population. In July 2016, more than 80 employees were assigned to the project.

Two of the defendants allegedly travelled to the US in 2014 to collect intelligence for their American political influence operations.

According to the indictment, the Russians also recruited and paid real Americans -- who did not know they were communicating with Russians -- to engage in political activities, promote political campaigns, and stage political rallies.

After the election, they allegedly staged rallies to support the President-elect while simultaneously staging rallies to protest his election.

For example, the defendants organised one rally to support the President-elect and another rally to oppose him-both in New York, on the same day, the indictment said.

On September 13, 2017, soon after the news media reported that the Special Counsels Office was investigating evidence that Russian operatives had used social media to interfere in the 2016 election, one defendant allegedly wrote, "We had a slight crisis here at work: the FBI busted our activity.... So, I got preoccupied with covering tracks together with my colleagues."

Muller is investigating into the allegations of Russian interference into the American political system. The opposition Democrats allege that Russian interference helped Donald Trump win the 2016 presidential elections. Trump denies the charges.