The officer volunteered to take part in a demonstration of the technology, which showed his blood alcohol level content was 80 mg per 100 millilitres.

However, the officer - based in the US city of Detroit - was not disciplined at the time because he was not armed nor had he driven to the class, WXYZ-TV reports.

However, he is now facing an internal investigation for being drunk at work.

Detroit Police Chief James Craig said: “The bottom line is that he showed up to work under the influence of alcohol. Certainly that’s a problem, it’s a problem for me, and it may be a problem on how it was handled after that.”