SEATTLE (REUTERS) - The US agency that investigates air crashes on Thursday called

for lithium-ion batteries on Boeing's 787 Dreamliners to undergo more testing to ensure they are safe.

The National Transportation Safety Board urged the Federal Aviation Administration to develop better tests for the uncontrolled overheating that led to a battery fire on a Dreamliner in 2013, require Boeing to conduct the tests, and check whether 787s, and possibly other planes, need more testing to ensure their lithium batteries are safe.