The Labour Party has boycotted Facebook for a month in solidarity with the Black Lives Matter campaign.
Frontbencher Rachel Reeves confirmed the party is not advertising with the site "at the moment" due to concerns about its policing of hate speech.
Officials confirmed reports in The Sunday Times that the party has cancelled thousands of pounds worth of adverts since the boycott began last week.
A party source added the boycott is only currently planned for the month of July.
Coca-Cola, Starbucks and Lego have all pulled adverts from the social media giant after facing pressure from the #StopHateforProfit campaign.
The campaign accuses social media giants of not doing enough to fight hate speech on their platforms.
Labour reportedly spent £1.2m in the last general election on Facebook advertising.
According to the Sunday Times, an email sent to senior Labour staff last week read: "This is a complete boycott, meaning we can't use Facebook to advertise anything at all and can't use it to boost posts."
Labour front-bencher Rachel Reeves told the BBC's Andrew Marr Show: "All MPs in the Labour Party use Facebook to get across our message.
"But what we're not doing at the moment is advertising on Facebook.
"And that is in solidarity with the Black Lives Matter campaign but also in line with what many businesses are doing this month, which is to express our concerns about the failure of Facebook to take down some hateful material from their platform and take more responsibility for the lies and propaganda that are sometimes put out there on Facebook.
"Facebook needs to do more to take responsibility and this is just one way that businesses and the Labour Party and others can put pressure on Facebook to do the right things and take tougher action on hate crime and hate speech."
