Roadside breath test checkpoints will be set up across four parishes for a week over the Christmas period.

A Government notice warned that road blocks would be operated by police every day from December 20 to Boxing Day.

The checkpoints will all be located in the central parishes – Hamilton, Devonshire, Pembroke and Paget.

Chief Inspector Robert Cardwell said: “Carrying out roadside sobriety testing is very demanding on resources.

“We have to be realistic about what we can and cannot do effectively.

“We feel that the central parishes is where the most risk is, that is not to say there is no risk in the west and east, we just cannot spread out further than the areas we published.”

Mr Cardwell admitted that some people might try to avoid detection by going out in parishes where checkpoints would not be in operation.

He said: “It is a risk. We hope common sense and the messaging about not doing this at all prevails.”