After an employee used a departmental credit card to spend nearly $9000 on what it has called illegitimate purchases, the Department of Foreign Affairs and Trade terminated their employment and is pursuing the funds through debt recovery.

DFAT told Parliament in a response to a budget estimates question on notice the staff member responsible for the $8,943 spend was an APS level employee.

Another three workers remain at DFAT after being caught using taxpayer-funded credit cards for purchases against departmental policy, but have been put on repayment plans.

The four cases amounted to $11,000 in inappropriate spending during 2016, DFAT confirmed.

"As per departmental policy, purchases are deemed to be illegitimate or contrary to agency policy when they are not an expense that relates directly to the core business of the department," a spokeswoman said.

"All departmental credit card use is subject to close scrutiny with careful monitoring of transactions."

Under DFAT credit card policy, using cards for private spending is prohibited, except paying an invoice that includes both official and coincidental private expenditure.

"In this circumstance, the cardholder must repay any private expenditure (including any associated tax) promptly and ensure it is identified in their acquittal statement," the department told staff.

DFAT has issued 2027 credit cards to employees with the largest single spend reaching $83,482 for embassy office rent in Doha, Qatar last year.

Credit card providers deemed 34 DFAT staff cards lost or stolen, but the majority of those were cards cancelled due to disputed transactions.

The department paid its workers' card debts on time in 2016, paying no late payment fees, and accumulating no interest charges.

Public service credit card use was thrown back into the spotlight when the government last month flagged a crackdown on inappropriate Defence Department staff spending.

The measures were outlined in the government's response to a 2016 Auditor-General's report on Defence's management of credit card and other spending, which found public servants had billed taxpayers for more than $3.3 million worth of events at private golf courses, sports memberships and entertainment over three years.

The damning report revealed taxpayers were charged for more than 1200 taxi trips between 1am and 4am over three years, when little work-related travel was required.

Responding to the audit recommendations, the department said it had enhanced forensic data and analytics capacity and its own internal audit and fraud divisions were stepping up reviews.

The Defence Department's internal auditor also reprimanded the agency for wasting public money after it racked up $20,000 in interest charges on late payments in one quarter last year.