(Reuters) - United Technologies Corp (>> United Technologies Corporation) on Friday said one of its units was responsible for a problem with fire-fighting systems discovered in some Boeing Co (>> The Boeing Company) Dreamliner jets.

Japanese airline ANA Holdings (>> ANA Holdings Inc) said on Wednesday that it had found an electrical wiring problem in the fire extinguishers of the engines on three Boeing 787s.

An assembly error at its service centre impacted some refurbished fire extinguisher bottles, a United Technologies spokesman said in an email.

"This error has been corrected and we are working with Boeing and the airlines to complete the necessary inspections, which we expect will be completed over the next few days."

Japan Airlines Co Ltd (>> Japan Airlines Co Ltd) also said on Wednesday that it was inspecting its Dreamliner fleet for similar problems.

The Wall Street Journal reported late on Thursday that the bottle-assembly at a Boeing supplier facility was responsible for the faulty fire systems.

(Reporting by Mridhula Raghavan in Bangalore and Lewis Krauskopf in New York; Editing by Joyjeet Das)