Kemal Kilicdaroglu, Turkey’s major presidential contender, claimed on Friday that his party had tangible evidence of Russia’s involvement in the production of “deep fake” web information ahead of Sunday’s presidential elections.

Kilicdaroglu, who has a slim poll lead over Erdogan two days before the election, told Reuters in an interview that Russia’s interference in Turkish domestic affairs was unacceptable, but that if elected, he would continue Ankara’s strong relations with Moscow.

NATO-member Turkey depends heavily on energy imports and Russia is its largest supplier. This week, two sources told Reuters that Ankara has deferred payment to Russia of a $600 million natural gas bill to 2024, underlining the extent of strengthened relations under Erdogan and Russian President Vladimir Putin.

Asked why he tweeted on Thursday that Russia was responsible for fake online content, a bold move, Kilicdaroglu said: “If we did not have it (concrete evidence), I wouldn’t have tweeted.” His party did not contact the Russian embassy over the issue, he added. He did not elaborate on what the online content was.

One presidential candidate from a small party, Muharrem Ince, withdrew on Thursday citing a faked “character assassination” carried out online. He gave few details.

Russia has been accused in the past of meddling in foreign elections including in the United States, which Moscow denies.

Turkey’s vote on Sunday shapes up as the most consequential in its modern history, with huge implications for Ankara’s global standing, strategic alliances and economic direction.

“We find it unacceptable for another country to interfere in Turkey’s election process in favour of a political party. I wanted the whole world to be aware of this, that is why I made this call openly by a tweet,” Kilicdaroglu said in an interview.

The Kremlin later denied interfering.

Kremlin spokesman Dmitry Peskov said the people who had passed on such allegations to Kilicdaroglu were liars and that Russia valued its ties with Turkey enormously.