Japan Post Co. says it may use drones to move packages between post offices, possibly as early as next year, due to the worsening shortage of delivery workers.

The envisioned project by the mail and package delivery unit of Japan Post Holdings Co. comes in the wake of e-commerce operator Rakuten Inc. and major parcel delivery provider Yamato Holdings Co. testing drone deliveries, but safety concerns remain about the new delivery method.

Japan Post is considering using drones in step with the government's pro-growth plan under which drone use is eyed for parcel delivery in mountainous regions in 2018 and in urban areas in the 2020s.

"We are aiming to fly drones between post offices in mountainous areas and remote islands," Japan Post Executive Vice President Seiki Fukuda said at a news conference Monday. For drone delivery to be put to practical use, Fukuda said that "how far regulations will be loosened" will be important.

Japan Post is planning drone delivery in rural areas because there is a smaller risk of the machine falling on people on the ground and because at post offices, workers will be able to receive packages directly. But the company will also need to ensure that drones do not hit electricity wires or lose packages.

Japan Post carried out experimental drone deliveries in fiscal 2016, aiming to someday deliver packages to doorsteps. On Monday the company also started seeking innovative business plans, including drone delivery, for startup firms. It will offer locations to test drones and consider providing capital.

In 2016, Rakuten tested drone delivery in the city of Chiba, flying drones loaded with packages between condominiums. Rakuten is aiming to eventually deliver products ordered through its online shopping mall.

Yamato Holdings also tested delivering small packages in Fukushima Prefecture in March.