President Donald Trump sacked at least a dozen internal government watchdogs late Friday, US media reported, the latest shake-up of the Republican's second term after less than a week back in office.

Independent inspectors general of at least 12 federal agencies were notified of their immediate dismissals via emails from the White House personnel director, The Washington Post reported, citing unnamed people familiar with the actions.

Inspectors general have an oversight role to detect and deter fraud, waste and abuse by government employees.

They are responsible for investigating violations of laws, regulations and ethical standards by employees, and conducting audits of contracts, finances and staff performance.

Among the federal agencies affected by the ousters were the departments of defense, state, interior and energy, as well as the Environmental Protection Agency and Social Security Administration, the Post said.

"It's a widespread massacre," said one of the fired inspectors general, according to the Post. "Whoever Trump puts in now will be viewed as loyalists, and that undermines the entire system."

Most of those fired were appointed by Trump during his first term, the newspaper added.

The New York Times, citing three unnamed people with knowledge of the dismissals, said 17 inspectors general were fired, and one source said the Justice Department's watchdog was not affected.

Democratic Senator Elizabeth Warren of Massachusetts called the firings "a purge... in the middle of the night."

"Inspectors general are charged with rooting out government waste, fraud, abuse, and preventing misconduct," she said in a post on social media platform X.

"President Trump is dismantling checks on his power and paving the way for widespread corruption."

On Tuesday, his first full day in power, Trump announced plans to weed out around 1,000 opponents from the US government.

The 78-year-old Republican began his second term with a flurry of executive actions aimed at overhauling government policies on immigration, citizenship, gender, diversity and climate -- some of which are being challenged in the courts.