Kairos, a small, solid-fuel rocket made by Japan's Space One, exploded just seconds into its inaugural launch on Wednesday as the firm tried to become the first Japanese company to put a satellite in orbit.

The setback for Space One and the rocket industry in Japan comes as the government and investors ramp up support for the sector amid a national security buildup and skyrocketing demand for commercial satellites.

The 18-meter rocket exploded five seconds after lifting off, leaving behind a large cloud of smoke, a fire, fragments of the rocket and sprays of firefighting water near the launch pad on the tip of the mountainous Kii peninsula in western Japan, visible on local media livestreams.

"The rocket terminated the flight after judging that the achievement of its mission would be difficult," company president Masakazu Toyoda said.

Space One has yet to determine the precise cause of the self-destruction that occurred after the first-stage engine was ignited – nor has it announced when it intends to launch the next Kairos – only committing to a thorough investigation into the explosion.

The company said that the launch is highly automated, requiring only about a dozen ground staff, and that the rocket self-destructs when it detects errors in its flight path, speed or control system that could cause a crash that endangers people on the ground.

"We don't use the word 'failure', because each trial brings us ... new data and experience for another challenge," Toyoda told a news conference.

There were no injuries near the launch pad, and the fire has been extinguished, Shuhei Kishimoto, governor of Wakayama prefecture, told reporters.

Kairos was carrying an experimental government satellite that could temporarily replace intelligence satellites in orbit if they fell offline.

Space One had planned the launch for Saturday but postponed it after a ship entered the nearby restricted sea area.