The WA Premier says there are lessons to be learned from the bungled docking of an export ship carrying crew infected with the coronavirus.

Six of the 48 crew aboard the Al Kuwait live export ship, which was allowed to dock in Fremantle on May 23, have been confirmed to have COVID-19.

The sick crew members are in hotel quarantine in Perth, while the others remain on board the ship.

The incident has sparked a row between Perth and Canberra, after the Western Australian government accused Commonwealth authorities of failing to tell the Fremantle Ports Authority that crew members were unwell while the ship was en route from the United Arab Emirates.

An angry Premier Mark McGowan demanded the federal government explain why state health officials found out by “word of mouth” from a Fremantle port worker.

However, he was forced to back down on Wednesday after federal Agriculture Minister David Littleproud released an email sent to WA health officials about the status of crew of the Al Kuwait on May 23. Mr Littleproud said state authorities did not act on the emails until Monday.

Mr McGowan said there had been errors all round regarding the Al Kuwait. Photo: AAP

Mr McGowan said he did not have that information on Tuesday. He said the email noted no concerns about COVID-19 on the ship, and did not request assistance from state authorities.

“That email had also been sent after the federal department had already granted approval for the ship to birth in Fremantle,” he said.

“I think this raises some issues that need to be addressed.

“There have clearly been some errors made all round. We can and must do better – and we will.”

Mr McGowan said the email should have “raised red flags” inside the WA Department of Health.

“We all know that the greatest risk to Western Australia at the moment is from people entering our state from overseas or from interstate,” he said.

“We have to be more vigilant.”

Earlier, the maritime union called for every seafarer on board the Al Kuwait to be tested for COVID-19.

“Make sure that the highest priority is their welfare, not to get the ship away from the wharf,” International Transport Workers Federation national co-ordinator Dean Summers told ABC radio on Wednesday.

Contact tracing is under way for the port workers, who are in isolation, and Mr McGowan has said he expects more crew to test positive.

He wants the vessel to set sail as soon as possible.

However, Mr Littleproud said the ship would not be able to return to the Middle East before the June 1 northern summer live export deadline, implemented in 2019 after the Awassi Express mass sheep death scandal.

He said the “independent regulator” – his own department – might grant an exemption.

“As far as I know, they’re ready to sail,” Mr Littleproud said.

“That can only happen after two things, firstly, there’s a deep clean of the boat, and crew are healthy enough to do that.”

The Maritime Union of Australia said the controversy showed the regulatory failures that allowed the Ruby Princess cruise ship to dock in Sydney, causing the nation’s biggest coronavirus cluster, had still not been properly addressed.

“The dreadful lack of co-ordination between federal and state agencies … demonstrates that the lessons of the Ruby Princess debacle still haven’t been learned,” national secretary Paddy Crumlin said.

Opposition Leader Anthony Albanese said the federal government was responsible for borders, and it was “quite extraordinary that they’ve been prepared to walk away from that”.

“[Home Affairs Minister] Peter Dutton is always trying to claim credit for controlling the borders except when it’s not convenient,” Mr Albanese said.

“It’s about time this government actually took responsibility for events that occur on its watch.”

-with AAP