A police bodyguard has been suspended pending an investigation, Scotland Yard has said, amid reports David Cameron’s passport and a loaded gun were found in the toilet cubicle of a British Airways flight from New York to London Heathrow this week.

The royalty and specialist protection unit officer’s passport was found alongside the former prime minister’s and all three items were handed over to flight crew, with the gun subsequently being removed from the plane, according to the reports.

“The captain confirmed a gun had been found, which freaked everyone out,” one passenger on the flight was quoted as saying.

The gun, believed to be a 9mm Glock 17 pistol, was reported to have been left by the officer after he took off his holster while using the toilet.

The Sun quoted an unnamed 33-year-old businessman who was on the flight as saying: “There was a real commotion going on with a guy near to me. He said he had found a gun in the toilets, which was met with disbelief … [The captain] tried to calm everyone down by explaining that the law allowed handguns on planes for protection officers and that the gun was back with the bodyguard.

“But a guy wasn’t having it. He said he felt uncomfortable about guns being allowed on the plane. The captain left and came back a few minutes later to say the gun had been removed from the plane.”

The paper quoted another unnamed passenger as saying: “We were waiting to take off when a guy started to show pictures on his phone of a gun and two passports. One was David Cameron’s – he said he found [it] in the toilet. They were just resting on the side by the sink. He was stunned by what he saw.”

Asked about the incident, which took place on Monday, Scotland Yard said: “The officer involved has since been removed from operational duties. We are taking this matter extremely seriously and an internal investigation is taking place.”

A British Airways spokeswoman said: “We follow CAA rules which allow UK police to carry firearms on board in specific, controlled circumstances. Our crew dealt with the issue quickly before departure and the flight continued as normal.”

