Donald Trump's son-in-law, Jared Kushner, used his personal email account on dozens of occasions in his capacity as a senior adviser to the US president to communicate with colleagues in the White House, his lawyer said
Between January and August, Kushner either received or responded to fewer than 100 emails from White House officials from his private account, attorney Abbe Lowell said in a statement on Sunday.
The use of a private email account to discuss government matters is a politically contentious issue that factored prominently in last year's US presidential election.
As a candidate, Trump repeatedly attacked his Democratic opponent Hillary Clinton for setting up a private email server as secretary of state - a decision that prompted an FBI investigation that shadowed her for much of the campaign.
The FBI recommended that no charges be brought against her, but noted she had been "extremely careless" in her handling of sensitive information.
In Kushner's case, Lowell said, the emails to and from his private account usually involved "forwarded news articles or political commentary and most often occurred when someone initiated the exchange by sending an email to his personal, rather than his White House, address."
The attorney said Kushner, husband of Ivanka Trump, uses his White House address to discuss White House business and that any non-personal emails were forwarded to his official account and "all have been preserved in any event."
Politico first reported Kushner's use of a personal email account.
Citing four officials, Politico said Kushner used a personal server to send messages to senior White House officials and outside advisers about media coverage, planning events, and other issues.
There is no suggestion the emails contained highly sensitive information or were classified, it added, but they could fall foul of the Presidential Records Act, which requires all documents related to the president's personal and political activities to be archived.
Kushner's numerous responsibilities within the Trump administration include brokering peace in the Israel-Palestinian conflict.
In an attempt to restart peace talks, Kushner, a key aide to Trump, met Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas on a Middle East trip earlier in August.
In addition to the email controversy, Kushner is facing scrutiny over the Trump campaign's alleged collusion with Russia to interfere in the 2016 election, which is the subject of multiple ongoing probes including by independent prosecutor Robert Mueller.
In June 2016, Trump's eldest son Donald Trump Jr, Kushner and then-campaign manager Paul Manafort met with a Russian government attorney who claimed to have incriminating information about Clinton.
Source: News agencies