Investigators say Boeing 787 Dreamliner fire is ‘not linked to battery’

British investigators said "at this stage there is no evidence" that a fire that broke out on an Ethiopian Airlines Boeing 787 Dreamliner at London's Heathrow airport on Friday was linked to the aircraft's batteries.

However, Britain's Air Accident Investigation Branch said "the initial investigation is likely to take several days."

The fire shut down the city’s main airport for an hour, caused major delays for air travelers, and sent shares of Boeing stock plunging on Friday.

Ethiopian Airlines said in a statement on Saturday that "the incident at Heathrow happened while the plane was on the ground and had been for more than eight hours" after a normal flight from Addis Ababa to London.

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It incident marks just the latest in a string of incidents plaguing the Dreamliners which were grounded in January due to battery problems.

External scorching could be seen close to the plane's tail, in a different area from the bays containing batteries, thought safety officials have not yet determined whether the fire was related to a battery problem.

Britain's Air Accidents Investigation Branch is leading the investigation, alongside the US Federal Aviation Administration and National Transportation Safety Board, Ethiopian Airlines and Boeing.

In addition to Friday's Heathrow fire, there was a separate incident that day with a Dreamliner flight run by Britain's Thomson Airways enroute from Manchester, England to Sanford, Florida.

On Saturday, Thomson's engineers were inspecting that Boeing 787 to determine why the plane, which reportedly had "technical issues" was forced to turn around during the flight.

Meanwhile, Ethiopian Airlines said it will continue to fly its Boeing Dreamliner aircrafts.

Boeing shares fell 4.7 percent  to $101.87 at the close of the markets on Friday.

Reuters contributed to this report