Google and Facebook are both considering new rules banning the micro-targeting of political ads, according to reports.

Critics of political advertising online have long worried that the ability to display specific messages to small sections of the electorate runs the risk of damaging democratic norms, by allowing candidates to present different platforms to different demographics.

The chair of the US Federal Election Commission, Ellen Weintraub, has called on Facebook to stop the practice. And in late October, hundreds of Facebook employees wrote to the firm’s founder, Mark Zuckerberg, asking for changes to how the company handled political ads, including limits to micro-targeting.

“The risk with allowing this is that it’s hard for people in the electorate to participate in the ‘public scrutiny’ that we’re saying comes along with political speech,” the employees wrote. “These ads are often so micro-targeted that the conversations on our platforms are much more siloed than on other platforms. Currently we restrict targeting for housing and education and credit verticals due to a history of discrimination. We should extend similar restrictions to political advertising.”

While Facebook has announced no action on any of the six requests made by the employees, on Tuesday, NBC News reported that Zuckerberg was considering limiting the ability of candidates to target narrow groups of users.

That report was followed by the Wall Street Journal, which said Google was considering the same change to its own political ad policy. The paper cited internal speculation that the “changes could be related to what type of audience targeting the company allows ad buyers to place”.

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The reports were welcomed by the Open Knowledge Foundation, which has been pushing for changes to both companies’ political ad policies. The organisation’s chief executive, Catherine Stihler, said: “It’s encouraging that online giants are starting to take their responsibilities seriously and recognising the need to act to stop the spread of disinformation.

“But this can’t just be left to social media platforms to take action by themselves – our analogue electoral laws need to catch up with the digital age and ensure we build a fair, free and open future.”

However, if the reports are accurate it is unlikely that any changes would be launched before the UK election, prompting Stihler to repeat an earlier call for both companies to impose a moratorium on political ads until the end of the campaign.