MENLO PARK, Calif. (Reuters) - Facebook Inc will ban false information about voting requirements and fact-check fake reports of violence or long lines at polling stations ahead of next month’s U.S. midterm elections, company executives told Reuters, the latest effort to reduce voter manipulation on its service.

The world’s largest online social network, with 1.5 billion daily users, has stopped short of banning all false or misleading posts, something that Facebook has shied away from as it would likely increase its expenses and leave it open to charges of censorship.

The latest move addresses a sensitive area for the company, which has come under fire for its lax approach to fake news reports and disinformation campaigns, which many believe affected the outcome of the 2016 presidential election, won by Donald Trump.

The new policy was disclosed by Facebook’s cybersecurity policy chief, Nathaniel Gleicher, and other company executives.

The ban on false information about voting methods, set to be announced later on Monday, comes six weeks after Senator Ron Wyden asked Chief Operating Officer Sheryl Sandberg how Facebook would counter posts aimed at suppressing votes, such as by telling certain users they could vote by text, a hoax that has been used to reduce turnout in the past.

The information on voting methods becomes one of the few areas in which falsehoods are prohibited on Facebook, a policy enforced by what the company calls “community standards” moderators, although application of its standards has been uneven. It will not stop the vast majority of untruthful posts about candidates or other election issues.

“We don’t believe we should remove things from Facebook that are shared by authentic people if they don’t violate those community standards, even if they are false,” said Tessa Lyons, product manager for Facebook’s News Feed feature that shows users what friends are sharing.

Links to discouraging reports about polling places that may be inflated or misleading will be referred to fact-checkers under the new policy, Facebook said. If then marked as false, the reports will not be removed but will be seen by fewer of the poster’s friends.

Such partial measures leave Facebook more open to manipulation by users seeking to affect the election, critics say. Russia, and potentially other foreign parties, are already making “pervasive” efforts to interfere in upcoming U.S. elections, the leader of Trump’s national security team said in early August.

A woman looks at the Facebook logo on an iPad in this photo illustration taken June 3, 2018. REUTERS/Regis Duvignau/Illustration

Just days before that, Facebook said it uncovered a coordinated political influence campaign to mislead its users and sow dissension among voters, removing 32 pages and accounts from Facebook and Instagram. Members of Congress briefed by Facebook said the methodology suggested Russian involvement.

Trump has disputed claims that Russia has attempted to interfere in U.S. elections. Russian President Vladimir Putin has denied it.

WEIGHING BAN ON HACKED MATERIAL

Facebook instituted a global ban on false information about when and where to vote in 2016, but Monday’s move goes further, including posts about exaggerated identification requirements.

Facebook executives are also debating whether to follow Twitter Inc’s recent policy change to ban posts linking to hacked material, Gleicher told Reuters in an interview.

The dissemination of hacked emails from Democratic party officials likely played a role in tipping the 2016 presidential election to Trump, and Director of National Intelligence Dan Coats has warned that Russia has recently been attempting to hack and steal information from U.S. candidates and government officials.

A blanket ban on hacked content, however, would limit exposure to other material some believe serves the public interest, such as the so-called Panama Papers, which in 2015 made public the extensive use of offshore tax havens by the world’s wealthy.

Months ago, senior Facebook executives briefly debated banning all political ads, which produce less than 5 percent of the company’s revenue, sources said. The company rejected that because product managers were loath to leave advertising dollars on the table and policy staffers argued that blocking political ads would favor incumbents and wealthy campaigners who can better afford television and print ads.

Instead, the company checks political ad buyers for proof of national residency and keeps a public archive of who has bought what.

Facebook also takes a middle ground on the authenticity of personal accounts. It can use automated activity it finds to disable pages spreading propaganda, as happened last week, but it does not require phone numbers or other proof of individual identity before allowing people to open accounts in the first place.

On the issue of fake news, Facebook has held off on a total ban, instead limiting the spread of articles marked as false by vetted fact-checkers. However, that approach can leave fact-checkers overwhelmed and able to tackle only the most viral hoaxes.

“Without a clear and transparent policy to curb the deliberate spread of false information that applies across platforms, we will continue to be vulnerable,” said Graham Brookie, head of the Atlantic Council’s Digital Forensic Research Lab.

(This version of the story was corrected to say that polling-place misinformation will be fact-checked, not that it will be banned outright in paragraph one; in 8th graph adds explanation of how reports on polling places will be handled)