TOKYO (AFP) - Japanese aviation authorities said on Friday they would allow airlines to resume flights of the Boeing 787 Dreamliner, following US approval.

"As the FAA (Federal Aviation Administration) is to approve the resumption as of Friday morning US time, we will take the same step," an official at the transport ministry said.

The US authority said on Thursday it would formally approve Boeing's 787 battery fix that will clear the way for the troubled aircraft to fly again.

The FAA's new airworthiness directive for the 787 requires the installation of modified battery packs and their respective chargers, as well as battery enclosures and ducts.

The FAA and other regulators grounded all 50 787s in service worldwide in mid-January after two failures of the lithium-ion batteries on the aircraft.

The latest FAA airworthiness directive caps a difficult three months for Boeing and its 787 customers, which have had to cancel thousands of flights and rearrange schedules after the worldwide grounding.

The FAA action technically affects just the six 787s of United Airlines, the sole US airline owning the aircraft.

Japanese airlines are the biggest customers of the high-tech airplane.