A stowaway has fallen to his death after clinging to the bottom of a British Airways jet as it flew over London.

The man is believed to have plunged from the aircraft and on to the offices of a clothes business in Richmond, south-west London.

A second man is in a serious condition in hospital after being found unconscious at Heathrow.

The pair are said to have held onto the plane as it flew more than 8,000 miles from Johannesburg in South Africa to Heathrow.

The stowaway is believed fell from undercarriage of plane. Credit: PA

A British Airways spokesperson said: "We are working with the Metropolitan Police and the authorities in Johannesburg to establish the facts surrounding this very rare case."

In a statement, the clothing business NotOnTheHighStreet.com said: "Officers and the London ambulance service attended and found the body of a male on the roof of the premises.

"The death is currently being treated as unexplained but early indications are that the body may be that of an airline stowaway."

The firm said the incident "is unrelated to the business or its team members" and they are co-operating with the ongoing police inquiry.

A stowaway fell on to the shop's roof. Credit: PA Wire

The company that runs Oliver Tambo airport in Johannesburg has confirmed it is investigating how the stowaways managed to get on to the plane.

Spokesman Colin Naidoo told ITV News Africa Correspondent John Ray: “Our security agents are working now with the police to try to establish the facts. We believe the person that survived is a male aged between 25-30, we don’t yet know his nationality."

A Metropolitan Police spokesperson told ITV News that it was investigating the incident.

On Thursday June 18 at about 8.30am, police received reports of suspect stowaway on a flight from Johannesburg to Heathrow.

Scotland Yard spokesman