Four more bodies have been found in the rubble of a collapsed Florida apartment building, a fire official said on Wednesday, raising the death toll in the disaster to 16 people.

Miami-Dade Assistant Fire Chief Raide Jadallah told family members at a morning briefing that rescuers found the bodies on Tuesday night. He said relatives have not yet been identified.

In addition to the four bodies, crews also found other human remains.

More than 140 people are still unaccounted for.

The discovery of the bodies came the morning after Florida authorities asked the federal government for an additional rescue team to comb the rubble of the tower.

The possibility that severe weather in coming days could further stretch Florida’s search and rescue resources prompted state officials to ask the federal government for the additional team, Kevin Guthrie of the Florida Division of Emergency Management said on Tuesday.

Already, intermittent bad weather has caused temporary delays in the search.

Mr Guthrie said the new team, which would likely come from Virginia, would be on hand if severe weather hits the area in coming days and allow crews that have been working at the site for days to rotate out.

Authorities said it is still a search-and-rescue operation, but no-one has been found alive since hours after the collapse on Thursday.

“There are two areas of (possible storm) development out in the Atlantic, heading to the Caribbean. We have eight urban rescue teams in Florida. We talked about doing a relief,” Mr Guthrie said at a news conference on Tuesday night.

“We have all the resources we need but we’re going to bring in another team. We want to rotate those out so we can get more resources out.”

The National Hurricane Centre says two disorganised storm systems in the Atlantic have a chance of becoming tropical systems in the coming days, but it is unclear at this point whether they would pose a threat to the US

Charles Cyrille, of the Miami-Dade County Office of Emergency, said 900 workers from 50 federal, state and local agencies were working seamlessly on the search.

Elected officials have pledged to conduct multiple investigations into the sudden collapse of the 12-story Champlain Towers South in Surfside last week.

Miami-Dade County Mayor Daniella Levine Cava said that she and her staff will meet with engineering, construction and geology experts, among others, to review building safety issues and develop recommendations “to ensure a tragedy like this will never, ever happen again”.

State Attorney Katherine Fernandez Rundle said she will pursue a grand jury investigation to examine factors and decisions that led to the collapse.

President Joe Biden and first lady Jill Biden planned to travel to Surfside on Thursday.