The fire hit a munitions depot storing various rockets that began to explode. Police evacuated at least 6,000 people from a 70 kilometer (42 mile) radius around the base in southeastern Ukraine.

Officials said they were unable to approach the site because of the explosions and the blaze could continue to burn for days. The blasts blew out windows and destroyed walls in surrounding villages and littered them with debris from various armaments.

"Such a fire cannot be put out just like that," said Defense Minister Evhen Marchuk.

He added neighbouring Russia was sending a specialist team to help and the United States, which is a major aid contributor to Ukraine, had also offered to help.

Medical officials in the region of Melitopol, the town near where the blasts occurred Thursday, said three of the dead were elderly people who had suffered heart failure after hearing the blasts.

The situation appeared to be turning more dire Friday when Grad installations that fire missiles with a range of 20 kilometers (12 miles) began to explode.

Even heavier missiles at site were not yet affected by the fire, officials said.

Officials stressed that the Zaporozhye nuclear plant several dozen kilometers away was safe.

Ukraine's head of the army chief of staff, Alexander Zatynaiko, said security services and the public prosecutor would launch an inquiry into the exact causes of the incident, amid speculation that the fire was set off by human error.

He added on UT-1 public television that no military personnel had died in the explosions. The defence ministry had earlier said a guard at the base had been killed.

The authorities said they had closed the railway line linking Moscow to the Crimea via Zaporozhye and halted road traffic through the area.

After the collapse of the Soviet Union in 1991, Ukraine inherited a total of 184 military arms depots from the Red Army. Most of the munitions were moved to a military base in Zaporijia, southeastern Ukraine.

In recent years, the Ukrainian armed forces have been hit by a series of accidents and mishaps which demonstrate the shoddy state of its military.

On October 10 last year, several thousand people were evacuated from their homes after a series of explosions ripped through a munitions dump at Artyomovsky in the Donetsk region of eastern Ukraine.

The explosions, also caused by a fire, shattered the windows of several apartment blocks and scattered debris as far as four kilometres (2.5 miles) away but caused no casualties.

In another tragic accident, 78 people died when a combat jet crashed during landing at summer air show, ramming into a crowd of people.

A year earlier during military excercises, a Ukrainian missile accidentally shut down a Russian airliner flying from Israel over the Black Sea, killing all 78 people on board.

Ukrainian military analyst Sehei Zhurets estimated that Ukraine now has two million tonnes of munitions it inherited from the Soviet era, "a part of which are no longer in working condition and waiting to be destroyed.

But that is not happening because the military had no funds to do so, he said.

Ukraine has expressed an interest in joining NATO as it tries to move out of the sphere of influence of neighboring Russia, with which it has at-times uneasy relations.

But the Brussels-based alliance says Ukraine must first invest massive funds into reforming the military and updating its equipment to NATO standards.

NATO is also concerned about Ukraine's human rights record, and media rights.

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