SAN FRANCISCO (Reuters) - Facebook Inc FB.O announced limited changes on Thursday to its approach to political ads, including allowing users to turn off certain ad-targeting tools, but defied critics' demands that it bar politicians from using its ads system to spread lies.

Ahead of the U.S. presidential election in November 2020, the world’s biggest social network has vowed to curb political manipulation of its platform.

Facebook failed to counter Russian interference in the 2016 election and allowed misuse of user data by defunct political consulting firm Cambridge Analytica. Now, it faces intense criticism of its relatively hands-off ads policies, especially after exempting politicians’ ads from fact-checking standards applied to other content.

Facebook said it and its photo-sharing app Instagram will soon have a tool enabling individual users to choose to see fewer political and social issue ads, and will make more ad audience data publicly available.

In contrast, Twitter Inc TWTR.N banned political ads in October, while Alphabet Inc's Google GOOGL.O said it would stop letting advertisers target election ads using data such as public voter records and general political affiliations. Online platforms Spotify SPOT.N, Pinterest PINS.N and TikTok have also issued bans.

A spokesman for the re-election campaign of President Donald Trump, which has spent more on Facebook ads than any other candidate, said the company’s approach to political messages is better than those from Twitter and Google as it “encourages more Americans to be involved in the process.”

U.S. Senator Elizabeth Warren, a leading Democratic presidential candidate, condemned the company on Twitter for “standing their ground on letting political figures lie to you.” She has called for Facebook’s breakup on antitrust grounds.

In a blog post, Facebook’s director of product management Rob Leathern said the company considered imposing limits like Google’s, but decided against them as internal data indicated most ads run by U.S. presidential candidates are broadly targeted, at audiences larger than 250,000 people.

Leathern wrote Facebook’s polices are based “on the principle that people should be able to hear from those who wish to lead them, warts and all.”

Facebook will roll out the expanded audience data features in the first quarter and plans to deploy the political ads control starting in the United States this summer, eventually expanding this setting to more locations.

CUSTOM AUDIENCES

Vivian Schiller, a news executive who has joined former tech employees and investors advocating for changes around the companies’ handling of political advertising, took issue with Leathern’s stance.

“Allowing the targeting of political messages to narrow slivers of the electorate is the opposite of enabling public debate,” said Schiller, who briefly headed the news unit at Twitter in 2014. “It’s akin to shadowboxing.”

FILE PHOTO: Stickers bearing the Facebook logo are pictured at Facebook Inc's F8 developers conference in San Jose, California, U.S., April 30, 2019. REUTERS/Stephen Lam

She said that once Facebook users share advertisements on their own feeds, the “paid post” labeling vanishes along with disclosures of who funded the messages.

Another change Facebook is introducing will be to allow users to choose to stop seeing ads based on an advertiser’s “Custom Audience” and that will apply to all types of advertising, not only political ads.

The “Custom Audiences” feature lets advertisers upload lists of personal data they maintain, like email addresses and phone numbers. Facebook then matches that information to user accounts and shows the advertiser’s content to those people.

However, Facebook will not give users a blanket option to turn off the feature, meaning they must opt out of ads for each advertiser one by one, a spokesman told Reuters.

The change will also not affect ad targeting via Facebook’s Lookalike Audiences tool, which uses the same uploads of personal data to direct ads at people with similar characteristics to those on the lists, the spokesman said.

Leathern said in the post the company would make new information publicly available about the audience size of political ads in its Ad Library, showing approximately how many people the advertisers aimed to reach.

The changes followed a New York Times report this week of an internal memo by senior Facebook executive Andrew Bosworth, who told employees the company had a duty not to tilt the scales against U.S. President Donald Trump’s re-election campaign.

Bosworth, a close confidant of Chief Executive Mark Zuckerberg, subsequently made his post public. He wrote that he believed Facebook was responsible for Trump’s election in 2016, but not because of misinformation or Trump’s work with Cambridge Analytica.

Rather, he said, the Trump campaign used Facebook’s advertising tools most effectively.