Several large explosions have been reported at a US military base in Japan.

Japanese broadcasting corporation NHK said emergency services are responding to a large blaze at a warehouse on the base at Sagamihara City, which is just outside of Tokyo.

The first of the blasts occurred just before 1am local time (2am AEST) but no evacuations have yet been ordered.

Social media users have shared photos and video of the blast.

No injuries have been reported.