Boeing has said that it will investigate a wiring defect that was found in a fire extinguisher system on three of its 787 Dreamliner jets.

The fault was found on jets operated by Japan’s All Nippon Airways (ANA).

The problem – the latest in a series of setbacks for Boeing’s 787 – was first discovered during pre-flight maintenance of a jet at Tokyo airport, an ANA spokeswoman said.

Rival Japan Airlines turned back a 787 travelling from Tokyo to Helsinki to check the wiring after ANA reported the fault on Wednesday.

It is the latest issue to hit the 787 jet after battery problems grounded the entire fleet earlier this year.

Boeing said it was aware of the latest issue and was looking into the matter.

“The safety of those flying on Boeing aeroplanes is our top priority. We will thoroughly examine this issue and take the appropriate steps,” the firm said in a statement.

In July, a fire broke out on a 787 Dreamliner jet operated by Ethiopian Airlines while it was parked at Heathrow airport.

The fire was traced to the upper rear part of the plane where a transmitter used to locate aircraft after a crash is located.

US carrier United Airlines also found a pinched wire during an inspection of one of its six 787s.

Boeing has since asked airlines to carry out inspections of the transmitters.

It has also asked operators of other aircraft models – the 717, Next-Generation 737, 747-400, 767 and 777 – to inspect aircraft.