Elon Musk has long considered Tesla Motors Inc the bold, nimble answer to the auto industry's cautious culture. Now the electric car maker's top executive has extended his help to another industrial giant: Boeing Co.

In a January 26 message on Twitter, Musk said he was in talks with the chief engineer of Boeing's 787 Dreamliner plane, which regulators have grounded indefinitely after a string of malfunctions ranging from fuel leaks to battery meltdowns.

"Desire to help Boeing is real & am corresponding w 787 chief engineer," Musk wrote on the social media website.

Musk, who is also the CEO of space transport company SpaceX, told Reuters in an email late on Monday that SpaceX battery packs could be helpful for Boeing.

"We fly high capacity lithium ion battery packs in our rockets and spacecraft, which are subject to much higher loads than commercial aircraft and have to function all the way from sea level air pressure to vacuum. We have never had a fire in any production battery pack at either Tesla or SpaceX," Musk said in the email.

Boeing declined to comment or confirm if such discussions were taking place.

Boeing's chief 787 engineer, Mike Sinnett, has recently made presentations about the plane and its battery technology to reporters and industry leaders.

Musk's post came a week after his first dispatch to Boeing on January 18: "Maybe already under control, but Tesla & SpaceX are happy to help with the 787 lithium ion batteries."

U.S. and Japanese authorities are investigating a fire and a smoke incident with lithium-ion batteries on two separate Dreamliners in recent weeks. The 50 Dreamliners in service cannot be flown until the U.S. Federal Aviation Administration is satisfied that the problem with the batteries has been fixed. The U.S. National Transportation Safety Board is still investigating what caused the first battery to catch fire.

Lithium-ion batteries are widely used in phones and hybrid cars because they are lighter and more powerful than traditional batteries. But if managed improperly, lithium-ion batteries can explode or catch fire, and some pose a greater risk than others depending on their chemical make-up.

The 787 is the first passenger jet to use lithium-ion batteries for back-up and auxiliary power. Tesla began using lithium-ion batteries in its Roadster, a two-door sports car that Tesla said could go from 0 to 60 miles per hour in about 4 seconds.

In its Dreamliner, Boeing adopted a lithium cobalt oxide chemistry similar to that used in the Roadster, which Tesla produced from 2008 until last year.

Musk, a serial entrepreneur who gained fame after selling his Internet payment company PayPal to eBay Inc in 2002, has been quick to criticize the cultures of major car makers like General Motors Co and Ford Motor Co.

In a magazine interview with Esquire late last year, Musk was similarly critical of Boeing. He was quoted as saying, "You know the joke about Boeing: It puts the zero in being."

Musk later took pains to dismiss the story, written by reporter Tom Junod. "Junod's Esquire article had high fiction content," Musk wrote his January 26 tweet.

Junod said Musk's dig at Boeing was on tape and his story was "more extensively reported than any story on Elon that preceded it."

(Reporting By Deepa Seetharaman; additional reporting by Nichola Groom, Alwyn Scott and Sakthi Prasad; Editing by Alwyn Scott and Chris Gallagher)