Pompeo was accused of abuse of power after he used an obscure emergency procedure to ram through $8.1 billion in arms sales to Saudi Arabia and other Arab allies in May of last year, despite opposition from the US Congress.

The Inspector General's report on the investigation has concluded that the State Department had "acted in complete accordance with the law and found no wrongdoing in the administration exercise of the emergency authorities that are available under the arms export control act," the senior official told reporters, speaking on condition of anonymity.

The official did not say when the report would be published, but the State Department released excerpts in a statement.

Congress had sought to block the arms sale in protest against the October 2018 murder of Saudi journalist Jamal Khashoggi, which was attributed by US intelligence services to Saudi Crown Prince Mohammed bin Salman.

Then-inspector general Steve Linick had been investigating Pompeo's 2019 declaration of an emergency that permitted the Trump administration to sell arms and bypass Congress, where lawmakers have voiced horror at civilian casualties in the Saudi-led offensive in Yemen.

Linick was also said to be investigating allegations that Pompeo and his wife used staff for personal favors such as walking their dog.

President Donald Trump fired Linick in May of this year on Pompeo's advice.

Linick's acting successor, Stephen Akard, abruptly resigned last week as his office was finalizing the report on Pompeo and the Saudi arms deal.

The department said only that Akard was returning to the private sector after years of government service.

Akard is a longtime aide to Vice President Mike Pence and his installation in May had widely been seen as a way to keep a friendly figure in the role.

According to the State Department press release, the report concluded that Pompeo's use of the emergency procedure was in accordance with the Arms Export Control Act (AECA).

The report said the emergency certification had been carried out correctly, and the documentation had followed regulations.

The report also said the same emergency procedure was used by five of the last seven US presidents, the State Department said in its statement.