There were no reports of deaths or injuries in the incident near the town of Ichnya, more than 170 kilometres (100 miles) from Kiev.

Prime Minister Volodymyr Groysman said on Twitter he was traveling to the site and emergency services later said he had arrived at the scene.

The fire and explosions began around 3:30am at the defence ministry's depot No. 6, which is spread over about 700 hectares (1,700 acres), the emergency services said in a statement. The size of the area affected was not known.

Almost 10,000 people were evacuated from the area at risk.

Authorities closed the airspace in a 30-kilometre radius around the site, as well as rail and road traffic.

It was the sixth major fire in three years at an arms depot of the Ukrainian army, which has been fighting pro-Russian separatists in the east of the country since 2014 in a conflict that has killed more than 10,000 people.

In March 2017, a huge fire set off explosions at a depot in the town of Balakliya in the Kiev-controlled part of eastern Ukraine, killing one person and injuring five others.

Ukrainian authorities blamed that incident on an "act of sabotage".