The investigation into the crash-landing of a British Airways Boeing 777 at Heathrow in January has revealed the likely cause to be the fuel system, and is considering whether exceedingly cold conditions made the fuel dangerously thick.

In an interim report the Air Accident Investigations Branch said a temperature of -76C over Russia on January 17 may have led to the thickening and reduced the fuel pressure, denying the additional engine-thrust required during landing.

The BA flight from Beijing crash-landed at Heathrow after a last-minute loss of power. It was the worst crash at the airport for 30 years, although only one of the 136 passengers and 16 crew suffered more than minor injuries.

No changes in operation for the more than 660 777s in service have been recommended and the investigation continues. No evidence of an aircraft malfunction has been found.