The engineering firm investigating what caused a large crack to develop on a concrete panel in Sydney’s Opal Tower has discovered more damage in the building.

The 34-storey building at Sydney Olympic Park was first evacuated on Christmas Eve – and again three days later – after a crack was found on level 10.

Engineers from WSP said they found two areas with “lesser damage” on level four but said apartment complex was “structurally sound overall”.

“As a precautionary measure, propping is being installed to support level four and this will be completed by Icon Co by the end of today,” WSP said in a statement.

“All involved parties are working cooperatively with the Government’s independent engineers, who are investigating the cause of the damage.

“There will be further investigative testing in relevant parts of the building.”

Icon Co is the construction company that built the tower.

In the statement, WSP warned residents on level four would not be able to return to their apartments until repairs were complete.

That could mean they are displaced for months.

The NSW Government has launched its own investigation into the tower’s structural integrity, appointing two university professors to write a report which will be made public.

NSW Minister for Better Regulation Matt Kean said developers in Sydney who had cut corners should be worried.

“If you’re a certifier who’s done the wrong thing, I will find you and I will throw the book at you,” he said.

“I will rub you out of the industry if you’re found to be doing the wrong thing.”

-ABC