Dominic Raab's bodyguard has been suspended from duties after leaving his gun on a plane.
The police protection officer had been travelling with the Foreign Secretary on a visit to the US when he left his gun on a plane at London’s Heathrow Airport on Friday.
The loaded Glock 19 pistol was reportedly found in its holster by a cleaner.
Scotland Yard confirmed the incident and said an international investigation is taking place.
A spokesperson from Metropolitan Police said: “We are aware of the incident on a flight into the UK on Friday, 18 September and we are taking this matter extremely seriously.
“The officer involved has since been removed from operational duties whilst an internal investigation into the circumstances is taking place.”
It follows a similar incident that occurred earlier this year in February when David Cameron’s bodyguard left his gun in a plane toilet.
The weapon, along with the former Prime Minister's passport and the specialist protection unit officer's passport, was found by a passenger in the cubicle of a British Airways flight from New York to Heathrow, according to reports at the time.
The items were handed over to flight crew with the gun removed from the plane.
It was believed that the close-protection officer removed his holster while using the toilet - which was carrying a 9mm Glock 17 pistol.
Mr Raab visited Washington this week to speak with senior figures including US Secretary of State Mike Pompeo on issues of Brexit and Northern Ireland.
The Foreign Secretary said he had had “very positive discussions” with Republicans and Democrats, after senior US politicians warned they will not support any free trade pact with the UK if Britain fails to uphold its commitments to Northern Ireland as part of Brexit.
Democratic Speaker of the US House of Representatives Nancy Pelosi, who also met with Mr Raab during his visit, said she “welcomed his assurances” but warned: “If the UK violates its international agreements and Brexit undermines the Good Friday accord, there will be absolutely no chance of a US-UK trade agreement passing the Congress.”
