Facebook has a new solution to keep an eye on who is buying US election-related ads: It's going analog.

The social network announced on Saturday that it will use postcards sent by US mail in order to verify the identity and location of people buying ads around the election, according to Reuters.

Facebook, along with Twitter and Google, has been heavily criticised by governments for not doing enough to prevent Russian organizations from buying ads as part of political disinformation campaigns.

Its announcement came a day after US special counsel Robert Mueller filed charges against 13 Russian nationals and three Russian groups for allegedly interfering with the 2016 election. Mueller singled out Facebook in his indictment, painting it as a critical platform in Russia's efforts to disrupt the election.

Facebook's global director of policy programs Katie Harbath said that the postcards will only be used for ads mentioning political figures. They will form one part of a broader to solution and aren't expected to solve everything, she told Reuters.