Rescue workers have freed four people who had survived under the rubble of a building in Kenya's capital for six days after it collapsed, the Kenya Red Cross says.

A woman was the first to be found, surviving in a cavity of broken masonry of the building that crumbled last Friday night.

Doctors had given her oxygen and fed her by intravenous drip until workers using their hands and power tools were able to free her.

Later in the day, the Kenya Red Cross said three more people had been recovered alive from the debris in the poor Huruma district of Nairobi, where the building collapsed after days of heavy rain.

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"Super news! Three more people have been rescued alive from the Huruma building collapse. One male and two female," the Red Cross said on its Twitter feed.

Witnesses said the first woman was carried to an ambulance to cheers and applause from a crowd at the scene.

The death toll from the disaster has reached 36, the leader of the operation Pius Masai told reporters. About 140 people have now been rescued.

Dozens are still listed as missing, but Kenyan Red Cross officials say it is not clear whether those listed were caught in the collapse or escaped but have not been traced.

Earlier this week rescuers had said there was little chance of finding more survivors.

A baby was pulled out of the wreckage on Tuesday, dehydrated but otherwise apparently unharmed.

The baby was reunited with her father, but Mr Masai said her mother was among those killed.

The Kenyan Interior Ministry said the building, built close to a river, had been earmarked for demolition, but local authorities had not acted on the order.

Two owners of the building and three local officials have been questioned by police and were released on bail on Wednesday.

The disaster was the latest of its kind in a rapidly-expanding city. Several other buildings in Nairobi have collapsed in recent years, with fewer deaths.

Reuters