'Cracked' Opal Tower residents moving out

The residents of a Sydney tower which "cracked" will be moved out for up to ten days while assessments are done.

The Opal's developer says it is 'pushing as hard as everyone else' to find out what went wrong. (AAP)

All residents of Sydney's cracked Opal Tower are being moved out as engineers work "around the clock" to figure out what caused Christmas Eve's structural failure.

Construction company Icon confirmed on Thursday they will moving all residents out of the building and put them up in hotels for up to 10 days while an investigation takes place.

"Icon confirms the building is structurally sound and the temporary relocation is a precautionary measure to allow engineers to work around the clock to investigate and remediate the site in the quickest time possible, without further disruption to residents," the company said in a statement.