Rescue teams have recovered more bodies from the rubble of a multi-storey shopping centre in Ghana's capital, Accra, which collapsed on Wednesday.Eighteen people are now known to have been killed - 69 were pulled out alive at the Melcom store.Faulty construction has been blamed for the collapse of the building which opened earlier this year.The owner of the building and the local government official in charge of building standards have been detained.President John Dramani Mahama said those responsible for the "negligence will pay a price".Rescuers on Friday had heard voices - but no survivors were found during Saturday.An Israeli rescue team has been using sniffer dogs to help locate people buried under the rubble.Officials from Ghana's National Disaster Management Organization have blamed poor foundations for the structure's weakness.On Thursday, the Ghana Institution of Engineering said the building did not have a permit, which meant the city authorities may not have inspected the building before it opened.The Accra Metropolitan Assembly ordered three nearby buildings which are also owned by Nana Boadu, the director of Kinsadus Company, to be evacuated.The property developer has said the Melcom store building did have a permit."There is no way I will put up a building and do a shoddy work," Mr Boadu told Ghana's Peace FM."Every document needed to help in the investigations I will provide. I have a file full of documents and receipts showing the building permit fees," he said.The president has declared the site a disaster zone and suspended his campaign for next month's elections.