Facebook on Monday acknowledged glitches in enforcing its policy on removing misleading political advertising for the US election after a report revealed banned messages were being recirculated.

The social media giant, which has faced intense scrutiny over its handling of political misinformation, said it took action after a media report showing loopholes allowing activist groups to repost ads that had been banned after third-party fact checks.

The Wall Street Journal report said some ads supporting President Donald Trump and containing false claims about Democrat Joe Biden had been reposted and shared by a conservative group after the original messages were blocked.

Facebook began removing the reposted ads after the Journal report over the weekend.

"When a fact-checker applies a rating, we apply a label and demote it while also rejecting it as an ad -- this is true for all ratings," a Facebook spokesperson told AFP.

"We reviewed these ads and are taking action on those that violate our policies, while also working to improve how we find similar ads to those that were already rated."

The Journal said the ads were being run by the American Principles Project, a conservative group, and contained false claims that Biden supports the far-left Antifa movement and backs sex change operations for children.

Last week, Facebook saw a rocky start to its effort to ban new political messages a week ahead of the November 3 election.

Rival parties complained new ads had been appearing despite the policy.

"We're investigating the issues of some ads being paused incorrectly, and some advertisers having trouble making changes to their campaigns," Facebook product manager Rob Leathern said in a tweeted message when the ban kicked in on Tuesday.

"We're working quickly on these fixes."

California-based Facebook has tightened its rules on political advertising ahead of the 2020 election. In particular, it has prohibited attempts to undermine the electoral process.