TOKYO (REUTERS) - Japan's transport ministry said on Monday that it has launched an investigation into the causes behind two fuel leaks on a Boeing 787 Dreamliner jet owned by Japan Airlines (JAL).

Over the weekend, the JAL jet, which was undergoing checks in Japan following a fuel leak at Boston airport last week, leaked fuel during tests. Both of the leaks were due to separate valve-related problems.

On Friday, the US government started a wide-ranging review of Boeing's 787 Dreamliner, citing concern over a battery that caught fire last week, also on a JAL plane, and other problems.

The US government and Boeing have insisted the passenger jet remained safe to fly.