An independent watchdog agency responsible for enforcing a law against partisan political activity by federal employees has opened an investigation into Jack Smith, the Justice Department special counsel who brought two criminal cases against then-candidate Donald Trump before his election to the White House last year.

The Office of Special Counsel confirmed Saturday that it was investigating Smith on allegations that he engaged in political activity through his inquiries into Trump. Smith was named special counsel by then-Attorney General Merrick Garland in November 2022, and his special counsel title is entirely distinct from the agency now investigating him. The office has no criminal enforcement power but does have the authority to impose fines and other sanctions for violations.

It was not clear what basis exists to contend that Smith`s investigations were political in nature or that he violated the Hatch Act, a federal law that bans certain public officials from engaging in political activity. Sen Tom Cotton, an Arkansas Republican, had earlier this week encouraged the office to scrutinise Smith`s activities and had alleged that his conduct was designed to help then-President Joe Biden and his vice president, Kamala Harris, both Democrats.