WASHINGTON — The Justice Department, accused by President Trump of “slow walking” its response to a congressional inquiry into the F.B.I.’s handling of the Hillary Clinton email case, said on Sunday that it was appointing a United States attorney to speed the production of documents.

The Republican-led House Judiciary Committee is examining actions by the bureau leading up to a decision in late 2016 by its director at the time, James B. Comey, to close an investigation into Mrs. Clinton’s handling of classified information on her private email server.

Mr. Trump has maintained that Mr. Comey, whom he fired last year, had acted inappropriately in closing the case, and that Mrs. Clinton, his opponent in the 2016 presidential race, should have been charged with a crime.

A Justice Department spokeswoman, Sarah Isgur Flores, said that Attorney General Jeff Sessions had requested the appointment over the weekend. The move was to be officially announced on Monday, she said.