Heathrow is "completely secure", the airport's chief executive has said following reports that a memory stick found in the street contained sensitive information about the flight hub.
John Holland-Kaye told MPs that the USB stick did not include information that compromised security.
He told the Commons Transport Committee: "From the information that I have seen... that was on the USB stick that was reported in the papers, there was nothing there that causes us any security concerns.
"So, from what I have seen, Heathrow is completely secure."
Mr Holland-Kaye said he was "disappointed" that the situation happened.
"We take safety and security very seriously and are very disappointed that this incident happened.
"We immediately set up an internal investigation to find out what happened, and that is ongoing. We have involved the Metropolitan Police in that investigation."
It had been reported that the memory stick contained files revealing information such as security measures used to protect the Queen at the airport, the types of ID needed to access restricted areas and the locations of CCTV cameras and tunnels linked to the Heathrow Express.