"Our email publication servers are under a targeted DoS attack since releasing #DNCLeak2," WikiLeaks said in a Twitter post.
On Monday, WikiLeaks released 8,263 emails belonging to the members of the Democratic National Committee (DNC).
"Friends, please remember that if you see a whopper of a Wikileaks in the next two days — it's probably a fake," member of Clinton’s electoral office Jennifer Palmieri said in a Twitter post.
In turn, WikiLeaks responded on Twitter that the "biggest whoppers" are those told during Hillary Clinton’s campaign.
The leak showed that the Democratic Party's top officials deliberately worked to obstruct Democratic presidential hopeful Bernie Sanders' campaign to favor Hillary Clinton's nomination bid.
WikiLeaks has also released thousands of emails from the hacked account of Clinton’s campaign chairman John Podesta.
In August, the website's founder, Julian Assange, pledged to release "significant" documents sent to or by Clinton's entourage before the presidential elections are held in the United States in November.