Only abortion-related ads from groups in Ireland will be allowed ahead of the vote.
This latest move will bring to €1bn the amount of money invested by Google in Ireland since 2003.
Anti-abortion group Save The 8th said in a statement: "Its scandalous, and it is an attempt to rig the referendum".
The Together for Yes campaign says Google's decision creates a "level playing field" between all sides. Yesterday, the transparency campaigner Gavin Sheridan tweeted that it was now his view that the No side would win the campaign because its online spending was dwarfing that of the Yes campaign.
The move is a significant U-turn after the Telegraph quizzed the search giant on its advertising practices last week, when it stood by its decision to show Irish people the search engine result: "vote no to abortion on demand - do you know the facts" at the top when they type "eight amendment" into the search bar.
Elsewhere, most of the country's biggest media publishers appear not to have banned digital ads that are related to the referendum.More news: Fitbit gets quick replies and menstrual cycle tracking
The news comes amid increasing focus on how online ads were used in campaigns like the Brexit referendum or the 2016 USA election.
Independent Senator Alice Mary Higgins rebutted McGuirk's comments, stating that "all sides are affected equally by this measure". The company will put a moratorium on all referendum-related advertising on its Google search pages as well as on YouTube in an effort to ensure advertising on its site doesn't tip the vote on the controversial topic. "That platform is now being undermined in order to prevent the public from hearing the message of one side", the pro-life groups said at a press conference.
Online targeting in the context of the upcoming vote was also a concern that was highlighted.
Google announced last week that it would be introducing a verification process for U.S. election ads as part of efforts to protect the integrity of elections.
Google is to suspend all advertisements related to Ireland's May 25 abortion referendum from Thursday amid worries about election integrity, the USA firm said in an emailed statement.
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