U.S. President Donald Trump's administration on Monday fired more than a dozen Justice Department lawyers who brought two criminal cases against him, an official said, as the Republican moves swiftly to exert greater control over the department.

The officials were fired after acting U.S. attorney general James McHenry, a Trump appointee, concluded they "could not be trusted to faithfully implement" Trump's agenda because of their role in prosecuting him, a Justice Department official said.

McHenry cited Trump's power as chief executive under the Constitution to justify the firings, according to a copy of the termination letter seen by Reuters.

The lawyers worked with special counsel Jack Smith, who led the two federal prosecutions of Trump that the department dropped after his November election. Smith resigned from the department earlier this month.

News of the firings came the same day that Ed Martin, the top federal prosecutor in Washington and a Trump appointee, opened an internal review into the use of a felony obstruction charge in prosecutions of people accused of taking part in the Jan. 6, 2021, attack on the U.S. Capitol, according to a source familiar with the matter.

The U.S. Supreme Court raised the legal bar for that offence in a 6-3 ruling last year, prompting prosecutors to drop the charge in several cases.

The moves reflect a willingness by the Trump administration to follow through on threats to seek retribution against prosecutors who pursued Trump and his supporters during his four years out of office.

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Tensions with Justice Dept.

Trump and his allies view the Justice Department with deep suspicion after prosecutors accused the president of national security- and election-related crimes.

Monday's moves came after the his administration already reassigned up to 20 senior career Justice Department officials, including Bradley Weinsheimer, the top ethics official, and the former chief of the public corruption section, Corey Amundson, from their roles.

Amundson, whose section provided advice to Smith's prosecutors, announced his resignation on Monday.

The moves to shake up the Justice Department's workforce have happened before the Senate votes on Trump's attorney general nominee Pam Bondi. Bondi's nomination is set to be voted on by a Senate panel on Wednesday.

Smith, who was appointed by former attorney general Merrick Garland, brought cases accusing Trump of illegally retaining classified documents at his Florida social club and attempting to interfere with the certification of the 2020 election.

Trump pleaded not guilty to all charges and argued the cases reflected a "weaponization" of the legal system.

Smith dropped both cases after Trump's election, citing a longtime policy against prosecuting a sitting president.

Many of those who worked on Smith's cases were longtime public corruption and national security prosecutors who remained in the department when Smith closed his investigation earlier this month.