Facebook blocked more than 100 Facebook and Instagram accounts with potential ties to a so-called Russian “troll farm” ahead of the U.S. midterm elections, the company said Wednesday.

The firm said it received a tip-off from law enforcement about the accounts, which it says may be linked to Russia’s Internet Research Agency (IRA), one of the groups that was indicted earlier this year over allegations it interfered in the 2016 presidential election.

Nathaniel Gleicher, Facebook’s head of cyber security policy, said the firm blocked the accounts on Monday night on concerns that they were linked to the Russian state-backed organization, adding that they “engaged in coordinated inauthentic behavior, which is banned from our services.”

The statement follows a previous announcement from Facebook on Monday, in which the company said it had shuttered 115 accounts — 30 of those being Facebook accounts and 85 being Instagram accounts.

“Almost all the Facebook Pages associated with these accounts appear to be in the French or Russian languages, while the Instagram accounts seem to have mostly been in English — some were focused on celebrities, others political debate,” Gleicher said in a blog post at the time.

On Tuesday, Facebook’s Gleicher said a website purporting to be set up by Russia’s IRA published a list of Instagram accounts which they claimed to have created.

“We had already blocked most of these accounts yesterday, and have now blocked the rest,” he said in Tuesday’s statement. “This is a timely reminder that these bad actors won’t give up — and why it’s so important we work with the U.S. government and other technology companies to stay ahead.”

According to reports, the website carried a message reading: “Citizens of the United States of America! Your intelligence agencies are powerless. Despite all their efforts, we have thousands of accounts registered on Facebook, Twitter, and Reddit spreading political propaganda.”

Facebook did not disclose any details about the pages.

It is not the first time the social network has been the target of Russia’s IRA. In April, Facebook removed more than 270 pages and accounts linked to the organization.

The episode highlights concerns of the potential for foreign actors like Russia and Iran to use social media to influence Western elections. Facebook recently banned 82 pages linked to Iran that were found to have been uploading politically charged memes.

Following 2018’s midterm vote, the Democrats regained control of the House of Representatives for the first time since 2010, while the Republicans made better-than-expected gains in the Senate.