Washington DC - National Security Advisor Mike Waltz, who has faced calls to resign over his role in the recent Yemen chat group scandal, saw renewed scrutiny Tuesday after the Washington Post reported on his usage of Gmail for official work.

The newspaper also said that one of Waltz's senior aides used Gmail to discuss military positions and weapons systems, reigniting questions over the handling of sensitive communications inside President Donald Trump's administration.

Waltz had his schedule and other work documents sent to his account on the Google email service, the Washington Post reported.

The White House later confirmed that Waltz had "received emails and calendar invites from legacy contacts on his personal email," but that he had "cc'd government accounts" since the start of the Trump administration to satisfy record retention laws.

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Waltz "has never sent classified material over his personal email account or any unsecured platform," said National Security Council spokesman Brian Hughes, who blasted the story as "the latest attempt to distract the American people from President Trump's successful national security agenda."

Hughes said he could not respond to the Washington Post report about Waltz's aide, claiming the newspaper had not shared the sensitive information with the White House.

"Any correspondence containing classified material must only be sent through secure channels, and all NSC staff are informed of this," he said.

Waltz last month provoked an embarrassing saga for the Trump administration after he inadvertently added The Atlantic magazine's editor-in-chief to a group chat on Signal, a commercially available messaging app, in which air strikes against Yemen's Houthi rebels were discussed.

Officials, including Waltz and Defense Secretary Pete Hegseth, used the chat to talk about details of the air strike timings and intelligence, unaware that the highly sensitive information was being simultaneously read by a member of the media.

Waltz told Fox News host Laura Ingraham last week that he took "full responsibility" for the breach, saying: "I built the group; my job is to make sure everything's coordinated."

Trump has rejected calls to sack Waltz or Hegseth and branded the scandal a "witch hunt."

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White House Press Secretary Karoline Leavitt meanwhile told journalists on Tuesday that "the case is closed, and the president continues to have confidence in his national security advisor."

But the Gmail revelations could add to pressure for Waltz's removal from office.