LOS ANGELES (Reuters) - A network of Russian-run Instagram accounts targeted Americans with contentious political messages ahead of next year's US presidential election, with Facebook camouflaged to appear as if they were from within the United States, Facebook said on Monday.

Facebook said it suspended these accounts on Monday, as well as three separate networks operating from Iran.

Facebook said the Russian network had "shown some links" with the Russian Internet Research Agency (IRA), an organization Washington said Moscow used to interfere in the 2016 US elections.

"We see that this process is largely aimed at the American public debate and is involved in some kind of challenging and sometimes contentious political issue in the United States right now," said Nathaniel Glischer, Facebook's head of cybersecurity policy.

US security officials have warned that Russia, Iran and other countries may try to influence the outcome of next year's presidential election, saying they are on high alert because of signs of foreign influence campaigns on social media, while Moscow and Tehran have repeatedly denied the allegations.

Glicher said the network linked to the Russian Internet Research Agency uses 50 Instagram and one Facebook accounts to collect 246,000 followers, about 60% of them in the United States.

He added that the latest calculations date back to January this year, and the process appears to be "somewhat immature in its development. They have focused heavily on building the public, and this is what you do first when you try to do something."

US security officials have warned that Russia, Iran and other countries could try to influence the outcome of next year's presidential election (Reuters)

Ben Nemo, a researcher at social media analysis firm Graphica, which Facebook commissioned to study recent IRA-related activity, said the reported accounts shared material that could appeal to Republican and Democratic voters alike. Conservative and progressive high-level.

This included comments initially shared on Twitter, criticizing US Congressman Alexandra Ocasio Cortez, Democratic presidential candidate Joe Biden and incumbent President Donald Trump.

"The interesting thing about this group is that a lot of what they were doing was copying and pasting original material from real US citizens," Nemo told Reuters.

The Iranian network is also active
He said a separate Iranian network identified by his team had used more than 100 fake and hacked accounts on Facebook and Instagram to target users in the United States, as well as some French-speaking areas in North Africa.

A subset of these accounts also republished the stories of Iranian state media, targeting users in Latin American countries including Venezuela, Brazil, Argentina, Bolivia, Peru, Ecuador and Mexico.

The activity was linked to an Iranian campaign first identified in August last year that Reuters showed was aimed at directing Internet users to a network of fake news sites that reprinted propaganda from Iranian state media.

Facebook said the accounts "are usually published on local political news and geopolitics, including topics such as public figures in the United States, politics in the United States and Israel, support for Palestine and the conflict in Yemen."