Dreamliner fleet was grounded by FAA in January after incidents of fire and smoke in the batteries of two planes

Boeing's 787 Dreamliner is set to fly again, after the US authorities gave the go-ahead Friday to a redesign of the plane's troubled lithium-ion battery system.

The Dreamliner fleet was grounded in January, after incidents of fire and smoke in the batteries of two planes. The global grounding came as just 50 of the planes had been delivered and was the longest of a commercial model in the jet age.

The company has been working on a solution with the Federal Aviation Administration (FAA). FAA administrator Michael Huerta said: "A team of FAA certification specialists observed rigorous tests we required Boeing to perform and devoted weeks to reviewing detailed analysis of the design changes to reach this decision."

"The FAA set a high bar for our team and our solution," said Boeing's chairman and chief executive, Jim McNerney. "We appreciate the diligence, expertise and professionalism of the FAA's technical team and the leadership of FAA administrator Michael Huerta and secretary of transportation Ray LaHood throughout this process. Our shared commitment with global regulators and our customers to safe, efficient and reliable airplanes has helped make air travel the safest form of transportation in the world today."

The FAA will publish regulations on how to alter the batteries in the US Federal Register next week, allowing Boeing and airlines to proceed with the fixes. The company is believed to have come up with a solution that involves greater separation between the batteries' cells and a venting system for any potentially flammable gases.

Top US safety inspector the National Transport Safety Board (NTSB) and Japanese authorities are still investigating the original causes of the two incidents, one in a plane parked at Boston's Logan airport and the other during flight in Japan.

The plane's grounding marked the first time since 1979 that FAA had banned every plane of a particular type from flying. That ban, on the Douglas DC-10, followed a fatal crash and was lifted within a month.

The 787's problems have been compounded by its hi-tech design. The Dreamliner is the largest passenger plane to make such extensive use of lithium ion batteries, which are lighter and can hold more energy than other types of batteries. The batteries, however, have also proved volatile and caused fires in smaller planes, cars, computers and mobile devices.

Next week the NTSB will hold the second set of hearings this month on lithium-ion batteries and the fire that broke out on the 787 at Logan. The NTSB chairman, Deborah Hersman, has been critical of the "assumptions" regulators used before clearing the ground-breaking use of the battery. The NTSB has also criticised Boeing for making statements "inconsistent with our expectations."