U.S. officials have warned that Russia may try to undermine the upcoming U.S. presidential election by spreading faked evidence of voter fraud, Reuters reported Thursday. Speaking on condition of anonymity, several intelligence officials said hackers may post photographs online purporting to prove the election was rigged with the help of voter fraud. They said they did not have any specific evidence to prove this would happen, but they have been warned about such attempts. Speculation about possible voter fraud has gained momentum after Republican nominee Donald Trump repeatedly claimed the election was being “rigged” against him, even claiming that voter fraud was prevalent at “polling places” before voting began for the Nov. 8 election. The U.S. government formally accused Russia of interference in the presidential campaign on Oct. 7 after several cyberattacks against Democratic Party organizations. At the same time, however, the officials cited by Reuters said they didn’t believe Russia would be able to succeed in swaying the election, though it could create a perception among the public that the vote was not fair.