Former West Australian treasurer Troy Buswell was using a taxpayer-funded credit card in Europe while researching light rail options when the state lost its AAA credit rating.
Documents obtained under Freedom of Information showed the former transport minister and his chief-of-staff Rachael Turnseck spent almost $14,000 on hotels, food, laundry and airport transfers during a two-week trip in August-September last year.
The Sunday Times reports Mr Buswell and Ms Turnseck toured the French countryside of Vrigny, in the Ardennes region, and nearby Tinquex where their dinner bill with Public Transport Authority director Mark Burgesss totalled $780.
The trip happened after last year's August state budget and in September when WA lost its AAA credit rating.
The head of Fisheries also went on the taxpayer-funded trip, the newspaper reported.
Before the trip, Mr Buswell said non-essential government travel would be temporarily banned.
The total cost has not yet been revealed, but a spokeswoman for Premier Colin Barnett said a report was submitted to the premier in January and would be tabled in parliament in the next couple of weeks.
The cost will also be included in the government travel report for the September quarter, she said.
Mr Barnett said on Sunday that overseas travel was expensive and such trips were often demanding on ministers who deserved to stay in good, but not excessive, accommodation.
"They have to eat, they have to travel, they have expenses, and international travel at a ministerial level is by its nature expensive," he told reporters.
Mr Buswell's trip to France, Switzerland and Germany, with stopovers in China, was his second trip investigating light rail, with a 2011 trip costing $33,559, The Sunday Times said.
In December, the light rail project was shelved after a review of the state's finances.
Mr Buswell recently quit cabinet and pleaded guilty to 11 traffic offences committed when he was driving home from a wedding in February.
He will return to parliament this week following his mental health issues and Mr Barnett said he expected the former treasurer to make some public comment.