KALYNIVKA - Ukrainian authorities evacuated more than 30,000 people Wednesday from the ce0ntral Vinnytsia region after a huge arms depot caught fire and set off explosions in what prosecutors said was a possible act of "sabotage".

It was the second major incident affecting a large Ukrainian weapons storage site this year.

Kiev blamed a deadly fire in March on Moscow and its Russian-backed insurgents fighting Ukrainian forces in the war-wrecked east - a charge both sides denied. The pro-Western former Soviet republic's military prosecutor's office said it was opening an investigation into possible "sabotage at a military facility".

Immediate reports mentioned no fatalities and only two minor injuries from the blasts at a facility the Ukrainian military said stored some 83,000 tonnes of munitions.

Military general staff spokesman Vladyslav Seleznyov told AFP that the arms depot was "one of the country's largest".

An AFP reporter said explosions in the town of Kalynivka in the Vinnytsia region located some 175 kilometres (110 miles) southwest of Kiev could be heard every five to 10 minutes and that streets of the town of 20,000 were nearly deserted.

"People suffered heavy damage," a local resident who agreed to identify herself only as Antonina told AFP. "Some homes had their windows and doors completely blown out," she said.

President Petro Poroshenko underscored the seriousness of the situation by telling his top military brass and Prime Minister Volodymyr Groysman to report to him directly after visiting the site.

"This is the arsenal of the Ukrainian army, and I think it was no accident that it was destroyed," Groysman said in televised remarks from the scene.

The military general staff later issued a statement saying an initial inspection showed that "around 70 percent of the storage facilities were not damaged by the fire."

The army's high command wrote on Facebook that the fire broke out at around 10pm (1900 GMT) Tuesday.

Police spokesman Yaroslav Trakalo told the Pravda news outlet the flames caused artillery shells at the facility to explode one after the other.

The national police said more than 30,000 people had been evacuated from areas immediately surrounding the storage facility.

"In addition, 180 patients were evacuated from Vinnytsia area hospitals," Ukraine's emergency ministry said.

Officials also shut down surrounding airspace as a precaution to keep exploding missiles from hitting passing commercial jets.

"Airspace has been closed in a radius of 50 kilometres (30 miles) around the area of the fire," Deputy Infrastructure Minister Yuriy Lavrenyuk wrote on Facebook.

The last major arms depot fire killed one person in the eastern town of Balakliya in March.

Authorities at the time pointed the finger at Moscow and Russian-backed militias fighting Ukrainian troops in a war that broke out in April 2014 and has claimed more than 10,000 lives.

Some officials in Kiev then mooted the possibility that the fire was caused by explosives dropped from a drone.

Both the Russian-backed forces and the insurgents dismissed the charge outright.

Vinnytsia lies nearly 700 kilometres west of the war zone. Russia vehemently denies plotting and backing Ukraine's eastern conflict and refers to the fighting as a "civil war" - a term that particularly irritates Kiev.