GWENT Police spent more than £700,000 on translators over the past six years.
The force needed to employ translators for dozens of different languages in this time, including Welsh, and spent a total of £717,493.
Translators are brought in to talk to suspects in crimes, as well as witnesses and victims.
In 2006/07, the force spent £75,225 on translators; this more than doubled the following year to £160,899 and peaked in 2008/09 at £172,247.
In November 2009, the Wales Interpretation and Translation Service (WITS) was set up, supported by the Welsh Government, other Welsh police forces and councils.
WITS finds bilingual people close to where they are needed, carries out security checks, language assessments and training and helped reduce costs to the police.
In 2009/10, the amount spent fell to £127,796, £83,529 before the introduction of WITS and £44,267 after, this fell to £95,348 in 2010/11 and £85,978 in 2011/12.
Between 2009 and 2011, Gwent Police paid a fixed rate of £36 an hour to translators.
Chief Inspector Tony Wilcox said: "All Police Forces have to comply with legal requirements to provide investigations in a language which people can understand. Without quality interpreters it would be impossible to conduct investigations involving victims, witnesses or offenders whose first language is not English or Welsh."
As well as languages one might expect translators to be needed for, such as Polish, French and Spanish, there was call for languages including Sylheti, spoken in North East Bangladesh, Krio, from Sierra Leone, Tagalog, spoken by people in the Philippines, and Tigrinyan, which is spoken by people in Ethiopia and Eritrea.
The force said it only kept a record of the list of languages it used translators for in 2010/11, when 41 translators were needed for 41 different languages.