A bitter war of words between two Tasmanian senators has intensified after one of them missed a vote in the Senate on Wednesday.

Australian Greens leader Bob Brown and senior Liberal senator Eric Abetz have been trading verbal blows over the payment of legal costs from a federal court case.

Senator Brown is relying on the financial assistance of his supporters to pay nearly $1 million in costs from the Wielangta case against Forestry Tasmania.

Had he been bankrupted by the legal bill, Senator Brown could have lost his upper house seat.

Senator Abetz has accused the Greens leader of being "ethically bankrupt", saying Senator Brown had already raised $739,000.

He launched an unrelated attack in the Senate on Wednesday, prompted by Senator Brown's request for a vote to be recommitted because he was inadvertently absent from the chamber.

Senator Abetz was not amused, reminding the Greens leader of comments he made during a previous sitting when a coalition senator missed a crucial vote.

"There was Senator Brown, high and mighty, condemning the coalition, being incompetent, unable to run themselves, what a rabble the opposition was," he said.

"Hypocrisy will hit you in the face like nothing else."

Earlier, Senator Brown accused Senator Abetz of being the Madame Defarge of Australian politics.

"He wants to sit at the guillotine knitting with other people's hair," he told ABC Radio.

"He's got nothing constructive to do whatsoever."

Senator Abetz should explain why the previous Howard government used public money to intervene in the Wielangta case.

"What he should do is explain the tens of thousands of dollars he as (the then) minister for forests put into this case from the public purse without asking," Senator Brown told reporters.

AAP