Boeing has been forced to postpone the first flight of its troubled 787 Dreamliner, its flagship new aircraft development programme, after discovering a weakness in the flagship structure of the jet.

Shares in the US aircraft maker fell by 6.5 per cent by the close of trading in New York after news of the embarrassing setback on Tuesday, which came only a week after Boeing said at the Paris Air Show that the start of the flight test programme was on track.