"We have so far recovered 30 corpses and the number of those rescued alive still stands at 13," Ibrahim Farinloye, from the National Emergency Management Agency (NEMA), told AFP.
A total of 12 bodies were recovered since rescuers resumed work today morning, he added.
The fatal collapse happened after heavy rains in the early hours of yesterday in the southeastern district of Lekki, which is home to some of the most expensive real estate in the city.
Some detached houses can sell for millions of dollars.
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Building collapses happen frequently in densely populated areas of Lagos, which is home to some 20 million people. Poor workmanship and materials, and a lack of official oversight are often blamed.
But collapses are rarer in wealthier districts.
The Lagos State government said in a statement that preliminary reports indicated work on the building was illegal but the order had been flouted.
"The collapsed building was served (a) contravention notice for exceeding the approved floors" and was sealed by the Lagos State Building Control Agency, it added.
The government called the owners' actions "a brazen act of defiance and impunity" and said "integrity tests" should be conducted on all projects being handled by the company.
All work has been ordered to stop at the site and the owners told to report to the police within 24 hours or face arrest, Lagos State information commissioner Steve Ayorinde said.