WASHINGTON, United States (AFP) — Twitter last Thursday announced new guidelines to clearly mark political ads on its platform as Facebook said it began implementing a policy requiring labeling and verification of identities of those paying for political messages.

The moves by the two social media firms come in response to criticism over their role in allowing disinformation to spread during the 2016 US election, in many cases with the help of automated “bots” or disguised Russian-based accounts.

Facebook said its new policy would be in effect as of last Thursday for ads in the United States on Facebook and Instagram. It intends to implement the same policy worldwide in the coming months.

Twitter, meanwhile, said it would begin enforcing a new policy in the coming months that would require “election labels” for US candidate ads and require notarised forms that verify the advertisers are in the United States.

Facebook’s announcement said it would verify the identity of those paying for ads — not just for candidates but for hot-button political issues — which some analysts have said may be difficult to enforce.