Facebook has removed an advert from a tax campaign group for breaking its rules on political advertising.
The Fair Tax Campaign, run by a former Boris Johnson aide, has been running an ad with the message "could you afford an extra £214 each month?"
It claims that this is what Labour's tax plans would mean for everyone.
Labour is yet to publish its tax plans or manifesto for the 12 December general election.
But Shadow chancellor John McDonnell this weekend said that if it won the election, the party only planned to increase income tax for the top 5% of earners to help fund increased public spending.
"In terms of income tax, we've said very clearly the top 5% will pay a bit more, 95% of the earners will be protected," he told the BBC.
A Labour spokesman called the banned Facebook ad "fake news" and said it was right that it had been swiftly removed.
The Fair Tax Campaign is run by Alex Crowley, a former aide to Prime Minister Boris Johnson. Mr Crowley left Downing Street in late September.
He told the BBC the ad made a "legitimate charge" that was based on a New Economic Foundation Report from August this year. He said the campaign had no links with the Conservative Party.
The message in the ad says "sponsored" but does not reveal who has paid for it. Under Facebook's rules, political advertisers have to register with the social media firm and every advert has to show who has paid for it.
Facebook removed the ad after being contacted by the BBC.
The company said it should have carried a "paid for by" disclaimer and the advertiser has been contacted "to provide clarity" on its policies relating to ads about politics, elections and social issues.
The Fair Tax Campaign will be able to switch the ad back on if they register and insert the "paid for by" disclaimer.
In the meantime the advert can be seen in Facebook's Ad Library, with a message explaining why it has been removed.
The group says on Facebook that it believes Labour's tax plans must never be allowed to happen and calls on voters to oppose them in the 12 December general election.
Three Facebook users contacted the BBC to say they had been shown the advert. They were responding to a crowd-sourcing initiative designed to reveal how the different parties are targeting paid adverts during the UK election campaign.
Facebook has come under fire on both sides of the Atlantic over its policy of not policing misinformation in political adverts.
Boss Mark Zuckerberg has repeatedly defended the policy, insisting that free expression must be his company's priority.
As the UK general election campaign gets underway, the social media platform is bound to be a vital campaigning arena, indeed it is likely to be the principal focus for party spending.
That means it will be vital to know just who is being targeted with which ads - so if you receive any in your Facebook feed over the coming weeks, do let us know! Email firstname.lastname@example.org