The Foreign Office has spent more than £1.3 million shipping staff members' cars to and from postings overseas for their private use in the last three years.
And more than half of that was spent in the last year, when some 86 vehicles were shipped abroad, and 27 brought back to the UK.
The Foreign and Commonwealth Office (FCO) has a policy of covering the cost of freight, marine and transit insurance and port dues, to enable staff to use their own cars in locations where suitable vehicles are hard to come by.
Staff are expected to sell vehicles before returning home, but in 42 cases over the past two years it was agreed to pay for them to be brought back to the UK.
Figures released in response to a freedom of information request showed that the bill for shipping vehicles abroad was £240,962.62 in 2011/12, £368,749.68 in 2012/13 and £704,078.65 in 2013/14.
But the FCO rejected a request to provide details of the dates, departure and arrival points and reason for each shipping, or the job titles of the car owners, on the grounds that it would be disproportionately expensive to compile the information.
"Costs vary year on year according to the number of staff moving between eligible posts. Some of the increase between 2012/13 and 2013/14 may be as a result of changing priorities for representation of UK interests overseas, which has seen the FCO increase the numbers of staff in some countries where car freight is allowed."