Twitter flagged a number of tweets from Democrats and those on the left who prematurely claimed Democratic nominee Joe Biden was declared the winner of the 2020 presidential race.

The posts were flagged amid complaints that the social media giant only censors users with conservative viewpoints.

A source familiar with Twitter’s actions during election week told Fox News that the platform took action against a number of Democrats, and left-of-center politicians and pundits who tweeted misinformation around the election and premature claims of victory.

TWITTER MARKS 12 TRUMP TWEETS AS 'MISLEADING' IN 60 HOURS

The source said many of the tweets referenced a “President-elect Biden,” despite the race not having been called for Biden or President Trump.

The platform flagged a number of tweets, including from former Democratic presidential candidate Andrew Yang, the co-founder of the Democratic Coalition Scott Dworkin, president for the Center for American Progress Neera Tanden, the chair of the Democratic Party in Wisconsin, among others.

The tweets were flagged with: “Official sources may not have called the race when this was Tweeted,” and linked to Twitter’s official “Election Results” page.

Tanden deleted her tweet once it was flagged, which stated: "Biden is already at 270 and his [electoral college] margin will likely grow with [Pennsylvania], and maybe even Georgia.  The mission was to defeat the monster.  And the monster is defeated."

Twitter’s actions came after Twitter CEO Jack Dorsey testified on Capitol Hill last week, and as the platform has been under fire for censoring conservatives and some stories that Republicans believed to be harmful to Biden’s campaign.

For weeks leading up to Election Day, Republicans decried Twitter’s actions to lock the New York Post’s Twitter account, and censor links to the newspaper's stories on Biden’s son, Hunter, and his overseas business dealings. Dorsey said this was due to a policy regarding hacked materials because the stories were based on emails from Hunter Biden's purported laptop.

TWITTER FLAGS TRUMP TWEET CLAIMING DEMOCRATS TRYING TO 'STEAL' ELECTION

Twitter, though, did take action flagging Republicans and conservatives during election week.

Twitter marked a dozen of President Trump’s tweets as misleading since Tuesday.

"Some or all of the content shared in this Tweet is disputed," the Twitter notice says. 

Trump and many of his supporters have gone on Twitter tirades this week as votes continue to be counted in the battleground states of Georgia, Pennsylvania and North Carolina, and the president's early leads have dwindled or vanished.

He and his team have promoted claims that those states are engaging in voter fraud, illegally counting ballots cast after Election Day and refusing to allow poll watchers close enough to observe the proceedings.

Several flagged tweets included video clips of Trump's press conference on Thursday, an address from the White House claiming, without evidence, that Democrats were trying to steal the election from him. 

In others, he declared himself the winner, despite votes in at least three states still being counted, and in one, he said, "STOP THE FRAUD!" 

Trump slammed Twitter for flagging his posts, calling the platform "out of control." The president has 88.4 million followers on Twitter, compared with 13.9 million for Biden and 121.5 million for former President Barack Obama.

Fox News' Vandana Rambaran contributed to this report.