The Federal Aviation Administration (FAA) said it is not close to approving test flights of Boeing's 787 Dreamliner with a proposed fix for the plane's troubled batteries, denying news reports that such tests could start as early as next week.

"Reports that we are close to allowing 787 test flights are completely inaccurate," spokeswoman Laura Brown said on Tuesday in an email to Reuters. Boeing declined to comment.

Batteries overheated on two jets last month, prompting regulators to ground the 50 Dreamliners in service worldwide. The grounding saddled Boeing Company with mounting costs and airlines with expensive planes that cannot be flown and in some cases are stranded far from their home airports.

Boeing proposed a multi-faceted fix for the battery system in a meeting with the FAA last week. The proposal included a stronger containment box, a battery with greater cooling capacity and other changes.

The proposed fix came before the cause of the burnt batteries is known. The National Transportation Safety Board is still investigating what caused one of the batteries to catch fire on a plane on the ground in Boston.

A second smoldered on a flight in Japan, prompting an emergency landing and evacuation. The Japan Transportation Safety Board is investigating that incident. Boeing has recently dispatched a new group of experts to Japan to work with battery maker GS Yuasa Corporation on fixes to the battery, according to a person briefed on the matter.

The Wall Street Journal, citing unnamed sources, reported that Boeing initially asked the FAA for flight tests to begin on Friday and told customers that if testing began in early March, the 787 might be allowed to resume operations with passengers by the end of the month.

But the FAA appears to have a different timetable.

In a notice issued last Friday, the agency alerted airlines operating the 787-8, the current production model, that they have until April 8 to submit comments on the decision to ground the aircraft because of unsafe conditions caused by the battery system. The agency said that in grounding the 787 on January 16, due to safety concerns after the two battery incidents, it did not provide time for public comment. – Reuters