The commonwealth has warned Rod Culleton to repay money paid to him when he was a Western Australian One Nation senator.

The high court unanimously ruled that Culleton was not eligible to run for the Senate at the time of the his election in July 2016 because of his larceny conviction, which was later annulled. He was disqualified under sections 44 and 45 of the constitution.

Jason Ford, the first assistant secretary, ministerial and parliamentary services of the finance department has written to Culleton about payments made to him for salary and other entitlements.

“I am writing to advise you that following the decision of the high court sitting as the court of disputed returns on 3 February 2017 that you were not eligible to be elected as a senator, payments made to you and in relation to you since the election on 2 July 2016 are a debt to the commonwealth,” the letter said.

The letter said the departments of both finance and the Senate had an obligation to pursue the debt.

“The Department of Finance is currently working to quantify the exact amount of the debt for which it is responsible,” the letter said.

Ford wrote the debt may include payments of superannuation, benefits such as entitlements and staff payments. Ford invited Culleton to consider his options, which could include providing evidence of his financial circumstances.

But Culleton, who was declared bankrupt in December, told Guardian Australia he was still in control of his assets and his legal avenues had not been exhausted.

Culleton said he would not be answering the finance department letter. “I’m just going to hang in like a flea in between the shoulder blades of a dog,” Culleton said, “right where it can’t scratch.”

He said the action would put other people off politics and accused the government of coming after crossbenchers to consolidate its hold on power.



“Do I really want to go back to the Senate?” he said. “To be honest, not really. But I would stay and run out the term to show you cannot come in and take out crossbenchers.”

The Department of Finance said it would “not comment on the work expenses of current or former parliamentarians”.