Japan's aviation regulators said on Tuesday there are still "several steps" required before any battery fix for Boeing Co's troubled Dreamliner jet can be approved.
Boeing said this week it was ready to make fixes to its batteries after regulators have approved the proposed solution.
The Dreamliner, Boeing's cutting-edge aircraft, have been grounded worldwide since two separate battery incidents involved the Dreamliner.
"In order for us to give the final okay, there are several steps we have to take," said Shigeru Takano, a senior safety official at the Civil Aviation Bureau.
(Reporting by Tim Kelly)