Investigators are looking into an emergency locator transmitter as part of a probe into a fire onboard an empty Boeing 787 Dreamliner on the ground at Heathrow.

The part, which sends out a distress signal if the aircraft gets into trouble, is made by Honeywell and uses a lithium manganese battery, Reuters claimed.

Honeywell confirmed it was helping around 25 experts, including some from the Air Accidents Investigation Branch and the US National Transportation Safety Board, with their inspection of the damaged Ethiopian Airlines 787.

A company spokesman said: “It’s far too premature to speculate on the cause, or draw conclusions.

“Our emergency locator transmitter have been certified by the Federal Aviation Administration since 2005, are used on a number of aircraft models, and we’ve not seen nor experienced a single reported issue on this product line.”

A preliminary investigation by the AAIB into last Friday’s incident appeared to rule out a link with the lithium ion batteries that grounded 50 Dreamliners in January.

Virgin Atlantic said it remained committed to taking delivery of 16 Dreamliners from the autumn of 2014.