Wednesday was supposed to mark practical completion of Perth's new $1.2 billion children's hospital after which the West Australian government would take control.

That will not happen, marking another delay for the troubled project being built by giant company John Holland and deputy premier Liza Harvey said the WA government’s patience was wearing very thin.

The original completion date was more than a year ago in late 2015 and since then lead-tainted water and asbestos-contaminated ceiling panels have been discovered amid other faults and delays.

Ms Harvey said the government wanted the hospital open before the March election but denied that was to ensure Labor leader Mark McGowan’s name was not on a plaque to open it if he won the vote.

“I would like to see it open in the very near future, which I have put to the contractor to get the job done to the standard we expect,” she told reporters.

“We want our children and staff from PMH (current children’s hospital) to be operating out of the new facility. We wanted that a while ago. We’ve been very patient but our patience is wearing very thin.

“Unfortunately a whole range of issues have occurred along the way, internal problems within the company that had the contract.

“It is not in the interests of John Holland and others involved in the construction of the children’s hospital to have this go on … it is bad for them and bad for the government and we accept that.”

Mr McGowan said the government should not rush to open the hospital before the election for political reasons when safety and health of the children who would be patients there should be a top priority.