Damaged battery of the Japan Airlines 787 plane
Media playback is unsupported on your device
Video

Boeing 787 Dreamliner tests 'missed fire risk'

Tests on Dreamliner batteries carried out by Boeing when they were first certificated for flight missed the high risk of fire, US regulators have said.

National Transportation Safety Board head Deborah Hersman said: "This investigation has shown that a short circuit in a single cell can propagate to adjacent cells and result in smoke and fire".

"The assumptions used to certify the battery must be reconsidered", she added.

The regulator also said it still had many more leads to investigate.

Go to next video: Dreamliner probe result 'weeks off'