Washington, Nov 6 Facebook has blocked 30 accounts on its platform and 85 accounts on Instagram that may be engaged in "coordinated inauthentic behaviour" from foreign entities into the US mid-term elections.

According to the social networking giant, US law enforcement contacted them about online activity that they recently discovered and which they believe may be linked to foreign entities.

"We immediately blocked these accounts and are now investigating them," Facebook said in a blog post late Monday.

"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," said Nathaniel Gleicher, Head of Cybersecurity Policy at Facebook.

American voters were set to cast their ballots on Tuesday in mid-term elections that will determine control of the US Congress and indicate how the country feels about Donald Trump's presidency.

"Typically, we would be further along with our analysis before announcing anything publicly.

"But given that we are only one day away from important elections in the US, we wanted to let people know about the actions we've taken and the facts as we know them today," Facebook said.

Facebook on October 26 removed 82 Pages, Groups and accounts for what it called "coordinated inauthentic behaviour" that originated in Iran and targeted people in the US and Britain.

The people behind these Pages and accounts represented themselves as US citizens, or in a few cases UK citizens -- and they posted about politically charged topics such as race relations, opposition to the US President, and immigration on Facebook and Instagram.

Facebook said about 1.02 million accounts followed at least one of these Pages, about 25,000 accounts joined at least one of these Groups, and more than 28,000 accounts followed at least one of these Instagram accounts.

In August, the social network removed 600 Pages and accounts originating from Russia and Iran for engaging in "inauthentic behaviour".

Facebook blocks more accounts 'meddling' in US mid-terms