The US has indicted two managers of a Russian state broadcaster and accused the Kremlin of a covert operation to interfere with November's presidential election.

Attorney General Merrick Garland said RT, formerly Russia Today, and two of its Moscow-based managers have orchestrated "a $10m scheme to create and distribute content to US audiences with hidden Russian government messaging".

Mr Garland also announced the Justice Department has seized 32 domain names used by Russian actors as part of the alleged influence operation.

Moscow's goal was to secure its "preferred outcome" in the race between Donald Trump and Kamala Harris, he said. 

Mr Garland added that the Treasury and State Departments would imminently announce their own actions as part of the Biden administration's efforts to "aggressively counter" the Kremlin campaign.

US officials warn that a growing number of foreign adversaries have attempted to interfere with its elections since Russia's efforts in 2016.

In June, a group of hackers linked to the Iranian government successfully breached Donald Trump's campaign and leaked internal documents.

A month later, the Department of Justice announced the seizure of two domain names and the search of nearly 1,000 social media accounts operated by Russian actors to "create an AI-enhanced social media bot farm that spread disinformation".

Researchers have also uncovered a growing Chinese influence operation aimed at infiltrating and swaying US political conversations on social media.

Xi Jinping, China's president, pledged his country would not interfere in the US election during a summit with President Joe Biden last November.

Jen Easterly, director of the US Cybersecurity and Infrastructure Security Agency, said on Tuesday that the US could "absolutely expect... foreign adversaries" to try to "undermine American confidence in our democracy... and sow partisan discord".

"And that's why it is up to all of us not to let our foreign adversaries be successful."

Eight years ago, Russia conducted a sophisticated campaign that involved hacking the Democratic National Committee and leaking stolen documents to Wikileaks with the intent of hurting Hillary Clinton's presidential campaign.

Many Democrats argue the operation helped contribute to Trump's eventual victory that November.

US politicians and intelligence officials have since concluded that the operation was directly ordered by Vladimir Putin, Russia's president.

Twelve Russian military intelligence officers were charged in 2018 with orchestrating the effort, and federal warrants were issued for their arrest.