Aviation company Boeing has halted deliveries of the 787 Dreamliner jet until concerns over lithium-ion batteries are resolved.

US and Japanese aviation safety officials finished an initial investigation of a badly damaged battery from a Dreamliner yesterday.

Boeing said it would continue building the carbon-composite 787. 

Safety concerns centred on its lithium-ion batteries, which are lighter than conventional batteries but are also potentially flammable.

However, deliveries were on hold until the US Federal Aviation Administration (FAA) approved and implemented a plan to ensure the safety of lithium-ion batteries that prompted a widespread grounding of the new airplane this week.

In Washington, the top US transportation official, Ray LaHood, said the 787 would not fly until regulators were "1,000 percent sure" it was safe.

A week earlier, Mr LaHood said he would not hesitate to travel on a Dreamliner.

Officials from the FAA, US National Transportation Safety Board  and Boeing joined Japanese authorities looking into what caused warning lights to go off this week on an All Nippon Airways Co domestic flight, prompting the aircraft to make an emergency landing at Takamatsu airport in western Japan.

The incident prompted regulators in the US and around the world to ground the 50 Dreamliners in service.

The jet has been flying safely for 15 months, carrying more than 1m passengers, but it has run into problems in recent weeks, including problems with fuel leaks.

When the FAA announced the grounding of all six US-operated 787s on Wednesday, the agency said airlines would have to show the batteries were safe and in compliance with its rules.

It said both battery failures released flammable chemicals, heat damage and smoke - all of which could damage critical systems on the plane and spark a fire in the electrical compartment.

A Japanese safety official at Takamatsu airport told reporters that excessive electricity may have overheated the battery and caused liquid to spill out.

Pictures released by investigators of the battery showed a burnt-out blue metal box with clear signs of liquid seepage.

GS Yuasa Corp, the Japanese firm that makes batteries for the Dreamliner, said it sent three engineers to Takamatsu to help the investigation.