WASHINGTON (AP) — A top House Republican has demanded details on the use of private emails by some of President Donald Trump’s closest advisers.

Rep. Trey Gowdy, a South Carolina conservative who chairs the House Oversight and Government Reform Committee, and the top Democrat on that panel, Rep. Elijah Cummings of Maryland, cite a recent Politico report that Jared Kushner set up a private email account after the election to conduct work-related business.

The New York Times reports that at least six of Trump’s closest advisers, including Kushner, Steve Bannon and Reince Priebus, used private email to discuss White House matters. Bannon and Priebus no longer work at the White House.

During the 2016 presidential campaign, Trump repeatedly attacked 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. Gowdy is best known for his two-year investigation into the 2012 attacks in Benghazi, Libya, in which he focused heavily on Clinton’s role as secretary of state.

In letters Monday to White House general counsel and State Department, Gowdy and Cummings said they want details on all employees.

“With numerous public revelations of senior executive branch employees deliberately trying to circumvent these laws by using personal, private, or alias email addresses to conduct official government business, the committee has aimed to use its oversight and investigative resources to prevent and deter misuse of private forms of written communication,” the lawmakers wrote.

White House press secretary Sarah Huckabee Sanders had no immediate comment Tuesday on the request by Gowdy and Cummings.

“All White House personnel have been instructed to use official email to conduct all government-related work,” she said. “They are further instructed that if they receive work-related communication on personal accounts, they should be forwarded to official email accounts.”

Sanders told reporters Monday that the use of private email accounts by staff was “to my knowledge, very limited.”

“White House counsel has instructed all White House staff to use their government email for official business, and only use that email,” she said, adding that “we get instructed on this one pretty regularly.”

Kushner’s lawyer, Abbe Lowell, on Sunday confirmed Kushner’s use of a personal email in his first few months of the administration. He said the emails usually involved news articles and political commentary. Lowell also said any non-personal emails were forwarded to Kushner’s official account and “all have been preserved in any event.”

Sanders would not say whether the White House would release Kushner’s private emails that dealt with government business.