BBC News: Airline safety inspectors have found no faults with the battery used on Boeing's 787 Dreamliner, Japan's transport ministry has said. The battery was initially considered the likely source of problems on 787s owned by two Japanese airlines.
It has raised fears that there will be no quick fix to a problem that meant all 50 787s in service were grounded.
Attention has now shifted to the electrical system that monitors battery voltage, charging and temperature.
Transport ministry official Shigeru Takano said "we have found no major quality or technical problem" with the lithium-ion batteries. Shares in GS Yuasa, which makes the batteries, jumped 5% on the news.
"We are looking into affiliated parts makers," he said. "We are looking into possibilities."