Facebook has delayed plans to introduce checks on verifying the identities of political advertisers as part of an initiative to tackle election interference.
Although the requirement was set to be introduced on 7 November, it has been pushed back following a series of embarrassing incidents in which the company failed to check if advertisers were who they claimed.
In April, Facebook's chief technology officer Mike Schroepfer told MPs that new measures to boost transparency on the social network would be introduced in the UK.
These would require anyone who wanted to run political adverts to complete an authorisation process. The campaigns would be accompanied by disclaimers noting they are "political" and displaying who paid for them.
However, a Facebook spokesperson acknowledged to Sky News that this process had been delayed following media reports which indicated it was easy to subvert the company's advertising checks.
They told Sky News: "We have learnt that some people may try to game the disclaimer system by entering inaccurate details and have been working to improve our review process to detect and prevent this kind of abuse.
"Once we have strengthened our process for ensuring the accuracy of disclaimers, we will be introducing enforcement systems to identify political advertisers and require them to go through the authorisation process."
It comes as the chair of parliament's digital, culture, media and sport committee criticised Mark Zuckerberg's refusal to attend parliament to be questioned by MPs.
Facebook say that they remain committed" to working with our committees "to provide any additional relevant information" that we require. Yet they offer no means of doing this. The call for accountability is growing, with representatives from 5 parliaments now meeting on the 27th pic.twitter.com/VJFtpqUi0r
— Damian Collins (@DamianCollins) November 7, 2018
The delays, which were first reported by The Guardian, came after some media outlets said they had successfully placed advertisements purported to be from contentious or proscribed groups.
Vice News in the US ran advertisements on Facebook which pretended to have been paid by parties including Islamic State and the US vice president, Mike Pence.
A similar report in the UK by Business Insider made anti-Brexit advertisements appear as if they were paid for by Cambridge Analytica, the defunct elections consultancy as the heart of Facebook's data scandal earlier this year.
Facebook has not said when the advertising rules would be enforced. A spokesperson said: "We will continue to roll out and refine these systems out over the next month so that we have a higher level of protection in place before next May's local elections."
Sky News technology correspondent Rowland Manthorpe said: "This news is extremely embarrassing for Facebook, which has been trailing its identity check system for some time as the solution to every political question that comes up (and there have been many).
The news that Facebook has delayed the roll-out of its identity checks on UK political advertisers after various utterly predictable issues makes me wonder how many things went wrong in the US in the time since it was first launched
— Rowland Manthorpe (@rowlsmanthorpe) November 7, 2018
"Bluntly put, the current arrangement doesn't work – which, given that it was already considered insufficient by many people working in the field, is extremely troubling indeed.
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"There are important questions here for Facebook. Can it fulfil its pledge to check the identities of political advertisers?
"And, if it can't, should it offer greater transparency by releasing advertisers' payment details?"