A huge fire at a military ammunition depot in Chad has killed at least nine people and injured 46 others, the health minister has said.

The death toll was in danger of rising as many of those wounded were in an "extremely serious" condition, Abdelmadjid Abderahim told journalists.

The explosions from the depot in the Goudji area of the capital, N'Djamena, lasted for about half an hour overnight.

Video footage showed them lighting up the night sky, with witnesses saying they could be heard miles away.

The weapons depot in Goudji is the country’s main arsenal and is in the north of the city near the military headquarters, two French army bases and the airport. There are also numerous residential houses in the neighbourhood.

Earlier, Foreign Minister Abderaman Koulamallah told French media the cause of the fire was accidental and far fewer people had died than had initially been feared.

"We were expecting dozens and dozens of deaths. In the end, the collateral damage isn't very big," Mr Koulamallah, who is also the government’s spokesman, told the AFP news agency.

"There aren't many civilians who lost their lives,” he said.

In his briefing, the health minister did not specify if those killed or injured were military personnel or civilians.

One resident told the Reuters news agency that he had been woken up to the sound of the explosion.

"Our house was shaking as if someone were shooting at us. Then we saw a big fire at the military camp and smoke and things exploding in the air," said Moustapha Adoum Mahamat.

"We could see artillery fly over us."

According to an official working with the French forces, there were “explosions of ammunition of all calibres".

"For the moment, no French military personnel have been wounded,” the official, who requested anonymity, told AFP.

On Wednesday morning, President Mahamat Idriss Déby visited the site of the incident and those receiving treatment in hospital.

After midnight he posted his condolences on Facebook and ordered an investigation in to the fire: "Peace to the souls of the victims, sincere condolences to the grieving families and a speedy recovery to the wounded.”

Mr Koulamallah, who had urged the public to remain calm in the immediate aftermath of the explosions, said an initial inspection suggested several people had been killed in the ammunition storeroom.

"The soldiers had time to evacuate the vehicles, heavy weapons etc and were able themselves to take shelter," he told AFP.

France currently has about 1,000 troops in Chad to fight jihadist groups across West Africa.

Chadian troops have also played a vital role in battling Islamist militants in the region.

The ruins of buildings can be seen at the site of the explosions

A huge crater can also be seen at the scene

Spent shells also littered the area

The explosions reportedly lasted for around half an hour

The military faces a huge clean-up operation