A search had uncovered the bodies of a further three staff who were helping to put out the fire that began on Thursday evening, spokesman Talgat Uali said.

Around 50 staff from the emergencies ministry had suffered injuries during the operation, he said.

"The (operation) to put the fire out continues," Uali told AFP.

The blasts occurred at a defence ministry ammunitions depot in the southern region of Jambyl, leaving scores injured and nearby villages evacuated by authorities.

A video shared on the Telegram messaging app showed a column of smoke billowing from a fire before a powerful explosion sent flames shooting out. Another video showed debris flying through the sky in long arcs as the fire raged.

The defence ministry said that a fire had broken out at the Jambyl ammunitions depot and "quickly spread to storage facilities where engineering ammunition is stored".

"The explosions stopped over time," the statement added.

Regular incidents at Kazakhstan's Soviet-era military depots have proved a headache for the government in recent years, with another depot near the southern town of Arys seeing three lethal explosions take place in the last decade.

The defence ministry noted that some of the munitions stored at the Soviet-era depot in Jambyl had been transferred from the facility in Arys, where there have been calls to resettle the town's entire population of 45,000.

At an emergency government meeting Friday, President Kassym-Jomart Tokayev said Kazakhstan had "systemic problems" with its ammunitions storage.

He called on authorities to investigate the disaster and provide help for the families of military personnel and rescuers who he said died "heroically in the line of duty".

- Arson probe -

The emergencies ministry said that the scattering radius of the fragments was up to two kilometres (1.25 miles).

"According to preliminary data, more than 500 tonnes of trinitrotoluene (TNT) were stored in the warehouse," the ministry said.

Defence Minister Nurlan Ermekbayev said Friday that he would leave his post over the incident if President Kassym-Jomart Tokayev accepted his resignation.

The Jambyl regional government said Friday morning that of more than 80 people who received treatment for injuries, 28 remained in hospital with six in serious condition.

But "their lives are not in danger," the statement said.

Tokayev said local residents had not been hurt during the incident.

The Jambyl authorities said more than 80 children were among those evacuated from nearby villages following the incident.

Around 1,200 people were taken to schools in Taraz, a city of over 300,000 people, which is about 30 kilometres (19 miles) from the facility.

A government commission has been set up to establish the cause of the fire, while Ermekbayev said arson was being considered as a potential trigger for the blaze.