Stolen credit cards were used to finance fake ads about Micheál Martin which originated in Russia and Belarus, the Tánaiste has said.
Mr Martin made the claims as the Government published its Defamation (Amendment) Bill on Thursday.
The Bill includes measures to “make it easier and less costly to tackle online defamation”.
He said: “I’ve been subjected to such online advertisements and fake ads and so on and it strikes me as extraordinarily challenging for individual citizens to seek the identity of such online defamers.”
The High Court previously issued a court order to force Google to hand over information about ads which suggested that Mr Martin was endorsing cryptocurrency companies, after the Fianna Fáil leader took legal action against the multinational on the matter.
Mr Martin said: “The fake ads seem to have originated from jurisdictions in Belarus and Russia.
“It seems that stolen credit cards were used to pay for the ads.
“Notwithstanding the fact that we’ve received a High Court order, I’ve written again to Google in respect of the ads that appeared on Google to get further clarity on the steps it intends to take because there seems to be a model of revenue generation here that’s unacceptable in terms of the proper application of the rule of law.”
Even with the court order, Mr Martin said forensic specialists had “great difficulty” going through the “enormous” amount of documentation from Google on the matter.
Asked if his criticism of Russia’s invasion of Ukraine was a factor in being targeted, Mr Martin said he did not know and could not make a definitive comment on the matter.
“We’ve had far less co-operation from X (formerly Twitter), who had a whole series of fake ads in respect of my good self and others in the midst of the local elections and advance of the referenda.”
Mr Martin said he welcomes the legislation addressing what he deems to be a “serious issue”.
He further warned that fake ads could undermine democracy in the middle of election campaigns.
X and Google have been contacted for comment.