Democrats have heavily criticised Donald Trump for firing a state department official who has reportedly been investigating secretary of state Mike Pompeo.
Steve Linick, who has been inspector general since 2013, will leave his post next month following the decision which was made public late on Friday.
In a letter to House of Representatives speaker, Nancy Pelosi, Mr Trump said he no longer had confidence in Mr Linick but did not give any more details on the matter.
“This is to advise that I am exercising my power as president to remove from office the inspector general of the Department of State, effective 30 days from today,” he said.
Although the letter did not name Mr Linick’s replacement, the US Department of State said his successor would be Stephen Akard, an ally of vice president Mike Pence.
The inspector general is the latest in a string of officials to have been dismissed in recent weeks, with Mr Trump flouting the tradition that watchdog roles are filled by non-partisan figures.
Eliot Engel, the Democratic chairman of the House of Representatives Foreign Affairs Committee, was among those who condemned the president’s decision.
Mr Engel suggested Mr Linick had been removed from office because he opened a probe into the secretary of state.
“I have learned that the Office of the Inspector General had opened an investigation into Secretary Pompeo,” he said in a statement.
Ms Pelosi said that the inspector general’s removal was part of a “dangerous pattern of retaliation” from the US president.
Glenn Fine, a top coronavirus watchdog, and Michael Atkinson, the inspector general of the US intelligence community, are among those who have recently been fired by Mr Trump.
Last year, Mr Atkinson was involved in triggering the president’s impeachment probe.
Additional reporting from Reuters
