At least 21 dead bodies have been recovered from a Nairobi supermarket devastated by a fire, police have said.

Eric Kiraithe, a police spokesman, on Friday said police were probing reports that exit doors of the  supermarket in the Kenyan capital were closed to prevent looters from entering when the fire broke out.

Nakumatt, the supermarket located in the south of Nairobi, was completely destroyed by the fire that broke out on Wednesday.

Nakumatt managers denied that the doors of the market were locked at the time of the blaze.

A company statement said the store "was fully fire safety compliant and had been installed with advanced fire/smoke detectors."

Witnesses said the high number of casualties may have been caused by exploding gas canisters inside the shop.

'Inadequate response'

Meanwhile, the Kenyan Red Cross said at least 47 people were reported missing since the fire broke out.

Mwai Kibaki, the Kenyan president, visited the scene, halting the recovery process for a short while.

"We will do what we can to assist all those who are hurt by this tragedy. We should come out and help each other," he said.

Some berated the emergency response as slow and inadequate.

"Ours is a modern city with an 18th century fire-fighting infrastructure," the Daily Nation, a Kenya newspaper, said in an editorial.

Raila Odinga, Kenya's prime minister who is representing east Africa's biggest economy at the World Economic Forum in Davos, Switzerland, also expressed concern.

"The fact that fire could gut down a business premise in a central place, a street from our fire headquarters... a stone's throw away from a major hotel says a lot about our disaster preparedness," Odinga said.