An explosion at an arms depot in the central Democratic Republic of Congo claimed more than 20 lives, the UN peacekeeping mission in the country said Saturday.

The city of Mbuji-Mayi "was ravaged with more than 20 dead, around 50 wounded and many destroyed houses" on Friday, MONUSCO said in a statement.

A government spokesman gave an initial toll of at least five dead from the blast triggered by a lightning strike on the military munitions dump at the Brigade army base, near the city's main market.

The UN said MONUSCO chief Martin Kobler had told the peacekeeping mission's local office to "help and support the local authorities to deal with the situation".

Government spokesman Lambert Mende on Friday told AFP that lightning had ignited a fire in the munitions dump and set off the explosion.

A witness speaking by telephone, who declined to be named, said he had seen the bodies of two people -- a woman and her child -- in the local hospital, as well as several people with amputated limbs.

On Saturday, witnesses said the explosion had burnt or destroyed houses within a radius spanning dozens of metres, leaving a crater around 1.5 metres (five feet) deep.

They said the arms had been stored under a metal roof.