The Attorney General of the United States met with the Russian ambassador twice in Washington during the presidential election campaign - something he did not disclose during the confirmation hearing, before his appointment by the Senate.

The meetings between Jeff Sessions and Russia's Sergey Kislyak took place in July and September, shortly before the presidential elections of Nov. 8 that were won by Donald Trump, amid political turmoil over Moscow's alleged interference in the electoral process, including through cyber-attacks.

The information on the meetings was revealed on Wednesday by The Washington Post newspaper after the incidents were confirmed by sources from the Justice Department, which is headed by Sessions.

A spokeswoman for Sessions confirmed that the meetings took place, but provided a statement from the attorney general saying they were not related to the election campaign.

“I never met with any Russian officials to discuss issues of the campaign,” Sessions’ statement said. “I have no idea what this allegation is about. It is false.”

However, The Washington Post contacted 25 other members of the committee to find out if they had had contact with Kislyak, 20 of whom said they did not.

Sessions, a former senator from Alabama who was among Trump’s most vocal supporters during the campaign, did not disclose the conversations when asked under oath during his Senate confirmation hearing in January about possible contacts between Trump’s campaign and the Kremlin.

When Democrats asked him about his alleged links to Kremlin, to which he responded: "I did not have communications with the Russians."

 "He was asked during the hearing about communications between Russia and the Trump campaign - not about meetings he took as a senator and a member of the Armed Services Committee," Sessions' spokesperson Sarah Isgur Flores told the Post.

The Justice Department and the Federal Bureau of Investigation - both under Sessions' supervision - are in charge of investigating alleged Russian interference in the elections, besides alleged links between Trump's campaign and the Kremlin.

Nancy Pelosi, the House Democratic leader, called for Sessions’ resignation. “After lying under oath to Congress about his own communications with the Russians, the attorney general must resign,” she said.