Police are working to identify a body that was found inside a British Airways passenger aircraft which landed at Heathrow on Thursday.
British Airways said the body was found inside the landing gear bay of a Boeing 747 after it arrived at the London airport from Cape Town, South Africa.
A company spokesman said: "We are liaising with the South African authorities and Cape Town airport after a body was found in the landing gear bay of one of our aircraft.
"They are investigating how this incident took place, which involved a Boeing 747 which arrived this morning from Cape Town.
"This is a very rare and sad event and our thoughts are with the individual's family."
The Metropolitan Police said the body was that of a man who was not a member of the jumbo jet's crew or a passenger on the flight. The death is not being treated as suspicious.
It is believed the dead man could be a person who was spotted scaling the fence at Cape Town International Airport last night before heading towards a BA flight getting ready to take off.
Airports Company South Africa, which runs the airport, said it was carrying out an investigation.
A spokeswoman said: "Last night at approximately 8.40pm a person was detected scaling the perimeter fence at Cape Town International Airport (CTIA).
"The airport immediately responded and, as a security patrol officer attempted to apprehend the man, he ran in the direction of a British Airways aircraft already in its holding pattern ready for take-off.
"For safety reasons the security officer could not approach the aircraft.
"A search of the airfield was immediately conducted but the person was not found."