The United States Postal Service has joined the growing list of airlines and online retailers cracking down on the hoverboard due to safety concerns, saying it will no longer carry the devices on airplanes for fear their batteries may be a fire hazard. The agency will still ship hoverboards using ground transportation like Standard Post.

"Effective immediately and until further notice, the Postal Service will ship the hoverboards only using Standard Post/Parcel Select, which travels on ground transportation, due to potential safety hazards pertaining to lithium batteries," a USPS spokeswoman told CNET in an emailed statement today.

The hoverboard — in reality a two-wheeled self-balancing scooter — has become a regulatory and legal nightmare of late. Many of the devices flooding the market this year are Chinese knockoffs manufactured by a sprawling network of overseas factories, resulting in questionable quality standards. Following high-profile reports of hoverboard explosions and battery-caused fires, US airlines have begun banning the vehicles as both carry-on items and checked luggage.

Online retailer Overstock has refused to sell the devices at all, while Amazon this week began removing some boards from its website citing open questions about their safety standards. Amazon reinstated popular seller Swagway, yet it urged UK customers of hoverboard maker RioRand to take its devices to certified disposal locations due to a faulty plug. Amazon says it's offering full refunds for the devices.