Facebook placed an informational disclaimer Tuesday on a post from President Donald Trump claiming mail-in voting would lead to a "corrupt" election.

The move, without removing the post, appears to follow through on the social network giant's pledge to step up efforts to fight misinformation, including from world leaders, shifting slightly from its hands-off policy on political speech.

Trump wrote on his page that mail-in voting, unless changed by the courts, "will lead to the most CORRUPT ELECTION in our Nation's History!" and added the hashtag #RIGGEDELECTION.

Facebook added an information tag which said, "Get official voting info on how to vote in the 2020 US Election" with a link to the government-sponsored USA.gov page on how to cast ballots.

Facebook has largely held firm to a policy that it would not fact-check political leaders, but it has pledged to take down any post which could lead to violence or mislead people about the voting process.

It recently promised to add labels to posts which would normally be removed for violating platform rules, but which are left online as "newsworthy," following the example of Twitter.

A coalition of activists has pressed Facebook to be more aggressive in removing hateful content and misinformation, including from the president and political leaders. Some 1,000 advertisers have joined a boycott aiming ramp up pressure on Facebook.