Mr McGowan says Mr Palmer has paid $445,700 in costs to the WA government in recent days.

But he said that left the state to cover the remaining $2,021,665 in relation to the initial defamation claim and the premier's counter-claim.

"Obviously that's a significant amount of money," the premier said on Thursday.

"I didn't start the proceedings. But the state and myself could not give in to Mr Palmer in relation to these matters.

"I'm frustrated like everyone. Frustrated by this set of events.

"This was very, very unfortunate."

Mr Palmer initiated the defamation proceedings in 2020 as the pair feuded over WA's COVID-19 response, particularly its border closures and claim for damages over a mining project.

In response, Mr McGowan issued his own defamation proceedings against the billionaire.

In August, Federal Court Justice Michael Lee ruled the pair had defamed each other, although he noted the premier had offered to settle the proceedings.

He ordered Mr Palmer to pay $20,000 to Mr McGowan, who was in turn directed to pay $5000 to the Queensland businessman.

"Both men went too far in their political jousting, and both men litigated, but only one was willing to draw back and avoid a long and costly hearing," the judge said.

Mr McGowan said it was important to remember what was happening in 2020 when the action was launched.

"It was in the context of the state of Western Australia doing its utmost to protect the state against COVID that was killing millions of people around the world," he said.

"We were essentially keeping the virus out and Mr Palmer tried to bring down the border at that point in time, which would have allowed the virus in."

In other action, Mr Palmer had sought up to $30 billion in damages over a 2012 decision by the former Liberal state government not to assess his proposed Balmoral South iron ore project.

The Labor government in 2020 rushed through extraordinary legislation to block the claim.

Mr McGowan said all together Mr Palmer and his associated companies had brought 13 legal actions against WA, its ministers or officers.

Two of those are ongoing, while the other 11 have either been unsuccessful or discontinued.

The premier said he regarded the defamation action as serious and believed he had to defend it properly.

"I was dealing with Mr Palmer. He's got billions of dollars in his pocket," Mr McGowan said.

"That's the circumstances that I faced."

Mr Palmer was in transit and unavailable for comment.

But in a response to the bill facing taxpayers, a spokesman urged the WA premier to personally "stand up and put the funds forward".

Australian Associated Press