The number of Eastern European felons imprisoned in Scotland soared to an all-time high of 126 in April 2014, with most hailing from Poland, Lithuania and Romania.
The costs, described as "completely out of control" by tax campaigners, have raised fresh fears about the record levels of immigrants that would be admitted in an independent Scotland to meet Alex Salmond's 24,000-a-year target.
There are currently around 300 foreigners in Scotland's 8,100-strong prison population. But the total number imprisoned in the last five years has exceeded 2,223 criminals of more than 50 nationalities.
Labour justice spokesman Graeme Pearson has argued that the immigrant prison population presents a rapidly growing problem which could worsen in an independent Scotland.
He said: "It is certainly disappointing and the cost will rise if more immigrants are encouraged to move to Scotland.
"One of the biggest challenges is the cost of translation services for the police as well as in prisons and the court system as it costs millions for interpreters and translators.
"The increasing strain also extends to the health service as well as education and the social services. You only have to go into a few Scottish schools to see that English not being the main language is a huge problem."